How to make replacement leather piston seals.  

With thanks to Unrepentantsinner for this extremely useful guide:

Figure 1

When I first got my BSA Improved Mdl D, I tore it down to inspect the seal, this is what I found, and the solution. I had read about making leather seals on the American Vintage Airgun Forum, I had made 1880 gun leather for years, so I suspected I had the skills to make the seals, I suspect you do to.

Figure 2

Here is a picture of the tools you will need. A dremel, a large hammer, a bench vice, a drill or drill press, file and sandpaper, 17MM or 11/16 socket, a 1" copper tubing union, two 2/4's about 1 foot long, a 1 1/8 wood bit, a drill bit the same size as the retaining screw on your piston, a hacksaw blade, pure silicone oil, dial calipers and utility knife.

Figure 3

First you need to drill one or more holes in the 2x4 with the 1 1/8 inch bit, 1/2 inch deep. This will be the mold for your leather piston cup. Then take the copper union and file a cutting edge on the outside of one end, this will be your leather punch.

Figure 4

Then cut 2 inch leather squares and also punch out a leather disk. Soak these in water with a drop of dishwashing detergent overnight.

Figure 5

Postion the leather squares over the holes you have drilled in the 2x4 and press the socket into the leather with the smooth side down with your bench vice. Allow to dry. Then press the leather disks between two 2x4's to expand them to .93 inches and allow the disks to dry. When the cups are dry, cut the excess leather on the cups above the board with a hacksaw blade. Then soak the cup and disk in pure or as pure as you can find Silicone oil.

Figure 6

Now find the center of the cup and drill a hole for the seal retaining screw assembly.

Figure 7

Now insert the disk into the cup and using the hole you drilled as a guide, drill the hole in the disk. You may have to clean up the inside of the cup with a dremel to allow the disk to fit.

Figure 8

Now disassemble your rifle, remove the seal retaining screw and replace the old seal with the one you have made. Now you must shape it to size, to fit into the compression chamber. The first one I made, I just rolled the piston on my bench top and filed and sanded it to shape. I have since made a spindle from a 10x24, 3 inch bolt and fender washers. I turned the washers down on my drill press with a file to .90 inches, as shown in figure 3. Now I can turn the seal while using the dremel to shape the seal. You will have a funny looking seal at first, there will be a rounded space at the bottom of the seal and top of the piston, this will disappear as you continuely work it in the rifle. Once it is the correct diameter to fit into the compression chamber, lube the piston and reassemble the rifle. I purchased my lube from The Airrifleheadquarters, moly lube and black tar lube.

Figure 9

Reassemble like in the old BSA hand book. Then work the piston by hand by cocking the rifle again and again. It will take a while for the rifle to start shooting at the correct velocity, as in any new seal replacement. ------------------------------

Unrepentensinner,

From Lakey:

Here is a short guide to dismantling a B.S.A underlever air rifle to inspect or replace the mainspring and piston head. It is the way I would do it.

All the main points are included but some people might tackle the task in a slightly different order. This is offered as a basic guide only and I recommend that you experiment and adopt the way that suits you best, but please remember to keep safety in mind at all times.

Before I start here are a few words of caution about tools.

When attempting to take one of these guns apart I would recommend the use of a gun maker’s turn screw, engineer’s drivers or other parallel bladed screwdriver. The gun screws on these guns have straight slots cut into their heads which are not suited to carpenter's/general screwdrivers which have a tapered blade.

If these unsuitable tools are used, damage can easily be done to the finish of the screw heads themselves which is difficult to remedy. Irreparable damage occurs because the tapered blade always wants to lever itself out of the slot when any pressure is applied to tighten the screw in question. If proper engineer's screwdrivers cannot be obtained, ordinary screwdrivers can be adapted by grinding the blade profile into a parallel blade.

How to dismantle a pre WW2 B.S.A Underlever Air rifle

Probably the main reason for dismantling the gun would be for regular service and in order to change the spring/piston washer. So I will describe this easy task first.

First, make sure the gun is not cocked and/or loaded.

Remove the trigger guard. This is done by removing the two or three (depending on the exact model of gun) screws holding the trigger guard in place and pulling the trigger guard free from the gun.

Next you need to unscrew the stock/trigger block from the cylinder. (On certain early guns such as some ‘H’ The Lincoln models, there may be a fourth screw holding the trigger block in place. You will see this on top of the compression cylinder just ahead of the trigger block. It also needs to be removed if present)

At this point it is advisable to have the end of the gun barrel placed against the floor (on a suitable pad to protect the muzzle crown). Using this technique you can lean on the stock continuously as you unscrew the trigger block and use your body weight to control the mainspring tension. (Some people prefer to clamp the cylinder in a soft jawed vice to leave both hands free to release the trigger bock).

You will need to pull the trigger back a little as you start to unscrew the trigger block away from the cylinder, but only for the first few turns, after which you can release the trigger. As you get near the end of the thread brace yourself to contain the sudden spring tension as the trigger block separates from the cylinder.

Once you have removed the trigger block/stock combination, you can gain access to the mainspring and piston. The spring guide on these guns forms part of the trigger block, so there is no need to worry about this being a separate component. Once the mainspring is removed, you can then go on to remove the piston.

In order to remove the piston from the compression cylinder, you first have to remove the short auxiliary cocking lever, just behind the larger hand cocking lever. This is done by unscrewing the auxiliary cocking lever pivot screw (and keeper screw if present), pulling the front of the lever down and disengaging the rear end from the cocking slot.

Once this has been achieved, a small screwdriver can be put gently through the cocking slot to push the piston back towards the rear of the compression cylinder eventually to emerge at the end of the tube.

At this point you can also remove the primary hand cocking lever by removing the pivot screw and lock screw (or round pin if a later model). After disengaging the front catch the cocking lever, you should be able to remove it from its recess below the breech.

If you want to remove the wooden stock from the trigger block, you need to either remove the metal butt plate by removing two screws at top and bottom (early models) or to remove the small oval wooden plug on the base of the stock (later models).

(If a later model, the oval plug will be secured with two dome headed wood screws and beneath the wooden plug there should be a curved spring steel washer, which pushes on the wooden oval making it easier to release. If the wooden oval is jammed in the hole, proceed very carefully and do not try to lever the wooden oval out, as they snap across the grain very easily and replacements are hard to find and even harder to replicate successfully.)

Once you gain access to the area behind the butt plate/wooden oval you will see a long hole with the head of a slotted bolt at the end. To remove the bolt you will need either a long, large flat blade screwdriver, or a flat bar bit attached to a brace or pair of mole grips (the large screwdriver is easiest!).

Once the bolt is loosened fully the stock should slide easily off the trigger block, but pay attention to the metal locating peg in the trigger block (this is often rusted or badly corroded)

Re-assembly is the reverse of the dismantling procedure.

I have not mentioned dismantling of the loading tap, as this part of the gun shows many variations and I will explain the different sorts of loading tap types in another post.

Lakey

BSA Air Rifle exploded views

Taken from R B Townsend's The Complete Air-Gunner, 1907:

From the Lincoln Jeffries catalogue 1906:

And from the 1915 USA catalogue:

Reproducing a No-8 peep sight base plate

Here's some measurement info to help you remanufacture BSA's original metal base plate for a no.8 peep sight (NB that this base plate was not made to fit on BSA air rifles originally - the screws could split the stock if you don't take care!)

This plate enables you to remove the sight and replace it easily and to protect the wood of the stock when doing so.

You will need to have a no.8 sight first in order to make one. Naturally the curvature of the plate matches exactly that of the base of the sight. Likewise, the tapped fixing holes match the holes in the bottom of the sight, so the exact spacing and size of these holes can be copied over.

The holes for the woodscrews that hold the base plate to the stock are approx 2.5mm in diameter and are countersunk. You could make these screws larger if desired. The original brass screws that came with my plate are 12.5mm long (half an inch).

All measurements are in millimetres and are only approximate - the best I could do by eye... Please note that some of the dimensions don't add up due to the fact of the plate being curved. But it shouldn't be hard to resolve the discrepancies by matching the plate to the sight base.

Eddie on removing seized bolts

Removing seized/damaged bolts etc. with welding

If anyone out there wants to download one and take it to a local welder to show what they want doing, it may help the explanation. I MUST emphasise that anyone who has even a little practise in TIG welding can do this, it's not a matter of great skill, only of having access to the equipment....

For the technos... I use an old Miller 275 (very basic set), and 0.40 size tungstens for small screws. Filler wire....alloy steel 4130 in 0.6 (mig wire) if I intend to reclaim the screw head, or if the screws are really knackered/seized, I use a tougher rod...Turbaloy M190 (jethete)......this is tougher than the screw itself after welding, and allows you to get some torque on.

In serious cases, I often use plusgas whilst the screw is still quite warm, and work it back and forth to get it going. Here goes then........the first job was a BSA standard cocking arm as Geoff described, I ground down an old damaged screw......this is just to show the small area it is possible to weld to without affecting anything close (you can go much smaller than this) The work area....

First "blob" deposited.....

Ready to remove with vise grips......

Out....(note limited heat input)

O.K.......now a challenge.......a poor old, destroyed diana (barrel blocked and drilled.....I only bought it for the wood)

Less than 5 mins. later......

self portrait.....

My workshop (well about half of it......nothing high-tech, but I would love all this in my garage

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Eddie on separating stocks from trigger block

Separating vintage BSA stocks from trigger block

The stuck stock bolt can be a nightmare, and often when you look carefully, the stock bolt is moving in the trigger block, but the either the stock bolt has rusted and expanded in the wood, or the wood has swollen tight onto the bolt......same effect, and often very hard to shift......have a very close look at the bolt end in the trigger block whilst moving the stock, if it is moving then there is a fix.

But it takes a bit of nerve and a steady hand......you will have to use a saw with the thinnest blade possible (junior hacksaw with a quality blade works well), and cut at the stock / trigger guard joint where the pin is....only go in deep enough (IN THE WOOD!) to sever the pin and reach the bolt, then, as the lug on the end of the stock is round, the stock will rotate off.

Shifting the bolt, however, can be really hard, but often a brass hammer will get it moving (careful...just a couple of mm, then tap back from the other end with a bit of rod)....It can split the stock in two longitudinally if you try and rush it, but slow and easy often loosens any loose rust....It is best to get the bolt rotating in the stock as freely as possible first, and it is not essential really to get the bolt out, just get it rotating.

You can get the stub of the pin out by simply building up the end with weld, and either weld a nut on and use a slide hammer, or twist out with decent visegrips (they are just a tooling pin, in quite soft steel, and are a light press fit when new....their job is solely to locate the stock in the correct orientation on assembly , but they often can cause splitting if guns either have been shot with loose stocks, or dis-assembled with loose stocks.

You then will have to carefully reshape the lug, and possibly shave a bit off the end (use a tiny blob of plasticene to check 'squish')....ie. if the stock bottoms in the block before being tight. You may also have to take a shave off the stock bolt corresponding to how much wood you have lost. ------------------------------

Eddie on removing dot punch marks 

Q. "I would also like to know the best way to correct a fault that some addle headed previous owner did to it...he decided to dot punch the dovetails to hold the sights and underlever catch in, how best to deal with these indents??? any ideas?"

Eddie: If the marks are centre punch, and really deep.......find a local welding company that does TIG, and you should be able to get these filled for the price of a pint...(obviously you will need to file the tiny pips of weld down). To colour match the area may be difficult however depending on how your gun looks now, they will blue / brown ok, but will take time to blend in.

If not deep, a gentle light repeated tapping with a jewellers, or similar weight hammer can be very good at reducing the displaced metal at the periphery of the indentation, work you way inwards and often they end up half the size.

It is really annoying to see guns that have had this treatment, when it is the work of seconds simply to remove the sight / latch whatever, and "close" the dovetail slot edges carefully with a small brass hammer, often this is all that is needed, but a smear of loctite (on degreased parts!) on very loose parts normally is a permanent fix......there are penetrating grades as well for fixing rear sights after zeroing.....on extreme jobs, a combination of a pad of blued shim steel to raise the offending item, and loctite is also a good fix.

I look for old sets of feeler gauges at car boots as donors.....you try some under the sight until it is a fairly stiff fit in the slot, then either use this size with locktite, or add a couple of thou and fit dry to enable zeroing if a rear sight...the grip will be as an original sight, and will last for yonks if undisturbed.....

I have one BSA I did this on 10 years ago which is still zeroed perfectly windage-wise.

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Lakey on adapting screwdrivers for gun screws 

Hi All, One of the biggest disappointments I find with collecting pre-war BSA's is the condition of many of the screws on otherwise good original guns.

The damage to these screws often results from owners trying to tighten or remove screws with general woodworking screwdrivers.

PLEASE DONT DO IT!

The trouble comes from the fact that general woodworking screwdrivers (ie not gunmakers turnscrews, or engineering screwdrivers)have tapering blades which are unsuited to the parallel sides slots cut into gun screws. Using general screwdrivers on gunscrews means that the more you try and tighten the gunscrew, the more the screwdriver blade wants to lever itself out of the slot, resulting in unsightly burring of the edge of the gun screw slot.

This damage is very difficult to remedy, and if you fit modern screws to these older, often patinated guns, they stand out a mile and tend not to match any original screws still on the gun. Here is a cheap way to make serviceable screwdrivers to use on your beloved airguns. Firstly I trawl various carboot sales looking for old cabinet makers screwdrivers such as the one below

I choose these older screwdrivers for the quality of the steel, and the fact that a good grip is afforded by the round wooden handles. They can be bought for very little money

(this one cost me 50 pence)

You can see that the traditional blade profile is totally unsuited to gun screws, as the sharp taper of the blade would probably cause damage if used on parallel sided gun screws. First thing I use is a dremel with a sanding drum, to reduce the sharp taper of the blade on both sides. Here is the same screwdriver after initial profiling of the blade

Then I transfer to an engineers metal file, and cut a small shoulder just above the tip of the blade, and then try and achieve more parallel sides to the blade, finally I fine tune the screwdriver to fit a given size of screw on the BSA rifle.

Therefore the width of the blade and the thickness of the blade are fine tuned to give me the purpose designed tool that I want.

Finally I temper the blade on the gas ring of the cooker and colour harden it to dark blue before quenching it in engine oil to cool it down. I find the dark blue colour gives me sufficient hardness without making the tip too brittle. Over the years I have collected a wide variety of sizes, so if it is the trigger guardscrew on a BSA Standard, or the tiny keeper screw on the auxillary cocking lever pivot screw on an improved model D, I have the correct size of driver ready and waiting.

Lakey

Eddie/Lakey (and others) on leaking taps, low power 

Q: "My BSA Standard has low power and I think the tap is leaking. Any ideas?"

<u>Eddie</u>: These taps normally are very good, one thing you could check is the serial number on the small end of the tap when removed (they were hand ground and matched to each gun originally)...It will be a two or three digit number, and if you look under the barrel (it may be necessary to remove the cocking lever in some cases to see this on some guns) there should be the same number stamped there as well....This was so when the actions were blued there was no need to keep these parts together as they could be re-united on the assembly bench.

If the numbers are different, you have a replacement tap......very rare, but not unknown. This would account for a bad leak in some cases.

The next thing to do if the numbers do not match is to check the alignment...ie is it central in the "load" hole?...a good check is to fire a pellet into a bin of cotton waste / shredded paper and check there is no 'clipping'...ie. the pellet is entering the bore centrally and has even rifling marks.

Mark the pellet with a marker to correspond with left / right when loading...this will tell you which way the tap is out...if it is in too deep, then metal spraying / plating as mentioned earlier is the only remedy, and you will need to regrind the tap in.....fine valve grinding paste, and a lot of care are the order of the day. If the tap is not deep enough, it can also be ground deeper the same way as just mentioned.

A replacement tap though is really rare...I have only seen two, on quite shabby 'bitsa' guns, and both were visibly out of alignment (in fact I have just tried 4 different loose taps I have in a Imp D action...not one is closer than 2mm out of line compared to the original, and all are different to each other!)

If the numbers do match: I presume you have done the normal check....ie. cock gun, open tap, then pull back the cocking lever and decock gun and control the cocking arm. as it is safe to release it, it should slowly move on it's own for a bit as the air pressure gradually escapes....a very few guns take ages, but normally 4-5 seconds shows all is pretty good.

Another thing to try is to 'black up' the tap with a quality permanent marker "pentel etc." and with the end retaining plate off the tap, press firmly with your thumb so the tap is seated, whilst rotating the tap through 360 degrees a couple of times...on withdrawing there should be bright metal showing through the marker in more places than not!...if there is just one small spot of rubbing, have a careful feel for knocks etc...this may be a high spot, which is preventing the tap fully seating, and can be very carefully stoned down, checking often by re-blacking and re- fitting.

Another thing I have encountered is a burr on the 'shoulder' where the tapered part of the tap ends, and the lever has a flat machined part...any damage here will hold the tap away from seating, as will a loose or replacement securing plate, or missing pressure spring.

Actually.....pull out the tap and check the groove in this area for burrs / debris as well...hardened grease build up can set rock solid over time!

And finally.....and often seen.....is the actual tap lever clear of the cylinder?...I have seen several bent enough to actually be touching when closed (usually caused by dropping at some time in the past)...normally there will be a 'witness mark' where the lever has rubbed the cylinder wall.

P.S. Check the tap is also not bottoming on something as well.....the pro's use 'plasigauge', but a tiny ball of putty / plasticine at the bottom of the tap recess should flatten, but still have some thickness when the tap is pressed in hard....all the bearing should be on the tapered part, so check for anything at the base, or hardened grease at the bottom of the tap pocket.

In a later thread responding to a BBS member who had renewed the springs in his Improved Mod D but was still experiencing low power, <u>Eddie</u> said:

Some easy things to try (problem in brackets);

Pull the tap out and look at the small end for a number, then look under the barrel...should be stamped there as well. (not original tap)

Then re-assemble with a light coating of grease and see if the power goes up substantially. (tap air leak)

Check washer is tight.

The piston with washer should be an easy sliding fit in the cylinder, not tight at all.(too much friction)

And also use an engineer's straight edge to carefully check for ''bulging'' in the compression area.(dieseling causing bad seal due to enlarged bore).

Look very closely at the joint between the cylinder and loading tap area, the cylinders are screwed on, and then soldered, but can fail over time, hold the barrel / cocking arm area, and with the stock / back block off, try and unscrew the the cylinder (normal direction)...The slightest movement will be a drastic lack of power...This will entail cylinder removal and re-fitting with loctite, and easy job, will advise if yours needs it.

<u>Lakey</u> added:

BSA made these guns out of the very best materials available at the time, and the steel used was first class. The loading taps are well made and fitted, and I can hardly think of an occasion when I found one leaking badly as the result of wear and tear. By the sound of things your tap seals really well, as I would expect.

Spring wear is the obvious one to fix first, and I see that you are on that.

I have to say your piston washer looked pretty good and undamaged, however they can harden with use, especially if the gun has been dry for a long while. The piston washer doesn't look too dry at the moment, but I have had success removing the existing washer, and then manipulating it in my fingers, getting some real flexibility back into the leather.

Whilst you are doing that look for obvious damage - a common one is that the leather splits at the back of the washer on the rear edge where it bends. If the washer is in one piece, and you've made it really flexible, try refitting the original washer and see how you go. That will save yourself a lot of time fitting and fettling a new washer.

Also, whilst the gun is in pieces, remove the loading tap and give the barrel a deep clean. That will improve on accuracy and could add to the guns velocity by a fair few fps. Let us know how you get on.

An addendum to this topic, based on replies to a BBS thread in January 2017 in which the OP, AndrewM, was worried that his Standard No.2's low power was due to a leaking tap.

Replies to his general enquiry included the following:

<u>Phil Russell</u>: "I have fiddled / meddled and generally cleaned up a fair few Standards in the past. They are very easy to work on but you do need to watch out for a strong mainspring at times. This is not an issue per se if you are careful on stripping the rifle but can give difficulty on reassembly unless you have a means of holding the action or end block captive while you compress the mainspring and start the end block threads going. Have you found the strip instructions on the Idiots Guide? Have a look if not, thread 112.
Regarding the tap ... If there is wear on the tap or indeed the hole in the action that the tap rotates in there is not a lot you can do without attracting expense. You may find a new tap from one of the spares suppliers (I have not checked) and it might well fix your problems but be prepared to maybe adjust the fit as I think most are supplied a tad oversize. And be careful to get the pellet bay in the tap exactly in line with the bore. Get it wrong and the pellet will 'clip' as it passes from tap to bore, losing power. In the past I have tried all sorts of remedies to cure leaky taps on all sorts of rifles and have not yet found an easy, cheap, reliable way of doing it. For an Airsporter I once resorted to making a new tap from the shank of a steel bolt. It worked but took a long time (my first attempt failed as I got the alignment out by a fraction of a mm). I believe it is possible to get a tap plated but do not know the cost.
You say the power is currently 8ft lbs. That is not too bad. Yes, I have heard of the Standard going up to 11 or above but I have never shot one at that level. I wonder if it becomes harsh? If the mainspring is very old then it could be weak and a slight increase over 8 may come from a new spring .. if I remember correctly you can fit an Airsporter spring.
Regarding the original Wasps... not very common. They do appear on 'the site' now and then and also at various auction houses on-line etc. But I have never bothered to search for them as I find most .22 pellets are OK in the Standard, although there are differences in power between them. I think Knibbs do a 5.6mm version of Marksman pellets if you want to give them a go. Do I remember the new Wasps being available in 5.6 and 5.5mm?"

<u>Lakey</u>: "I am lucky enough to own a few standards, and on the whole, they are a largely bomb proof design. They were made using exceptionally good quality steel, which means that bad wear is unusual.
The loading tap is also quite an efficient fitment that is usually pretty airtight. The loading tap on a BSA standard is secured with two screws, which hold the keyhole shaped block in place. These two screws need to be tight. There is a spring loaded plunger pushing against that plate, and if it is not absolutely tight, the tap can leak.
I wouldnt get too hung up on the tap test - with the whoosh as you describe it. Far better to make sure that you have a well lubricated leather washer in place, and a good spring (or springs, as some guns have two smaller springs in place of the one single mainspring.)
Sometimes a really good barrel clean, can both improve velocity and accuracy combined. I have occasionally discovered scored compression chambers, which can affect power, and also the main leather washer can be a bit dry, which will also have a negative affect on velocity.

BSA standards started off, with the main leather washer, and small inner washer held in place by a single flat headed screw and brass dished washer ( the large head of the screw fitting flush into the front of the dished washer), however after about 1930, the washer was held in place using a round nut, which screwed directly onto the front of the main piston shaft. These pistons were heavier and longer, and consequently a bit more power was possible.
BSA designed these guns to have the leather piston washer regularly lubricated with a few drops of oil, every few hundred shots, so I guess limited dieseling was factored into their operation. Check out Danny Garvins fabulous vintage BSA website for more info."

<u>Eddie</u>: "Don't stress too much about the static pressure test on the tap, I have a 1911 45 inch Sporting (basically the same as a Standard) which lets the cocking arm go forward against the tap quite quickly.......but makes 11.6 foot pounds

They take a good while to settle down after a re-seal, up to 1000 shots or more I have found unless you really faff with sanding the seal to get a light sliding fit dry...then it expands when oiled but seems to take less running in.

Pellet choice can be a tradeoff between power / accuracy and smoothness of shooting...do not use anything that makes the gun feel harsh or slammy IMHO, no matter if making power.

H+N FTT in 5.54 head size work really well and gives super long range (40-80 yards) accuracy even better than original Wasps in extensive tests I have done (In my 2 guns anyway)...But (original) Wasps are super out to 45 yards.

The sportings make the most power of any 45 inch gun due to longer stroke, Standards in good order can make 11 but most are mid 10's I have found. Spring choice makes a big difference and yours might just need a new unit / experiment...Just because a certain person has rebuilt it does not mean it has the most efficient unit, it will be whatever was in stock / to hand

Don't overthink these, you can have the back off and all the internals out in 5 mins, or a spring change in less than that.

If mine I would pull apart, check security of seal retaining the screw, try piston fit by dropping down cylinder, a full power fit will be the slightest pressure push to move it...if stiffer it needs more shooting in, and if stiffer there is more power to come so leave the fitted sping, just relube and get some lead through it and re-test after a min of 500 shots, it may well have gone up.

If seal looks good and piston moves easily, and you are desperate for more power then maybe try a replacement spring and see.

Tap wise, check end cover screws are snug, I have lost count of the guns I have seen where these are a tad loose but the indent plunger and it's spring fitted into the drilling in the tap itself normally (not always if not original) will keep the tap seated. Leaks are really really really rare...trust me.

One last thing I suppose as the tap seems to concern you, remove the cover plate and pull out the tap, check the numbers stamped on the end of the tap and compare to numbers stamped under barrel (sometimes up near cocking pivot) as taps are matched to each gun so this will confirm if original unit.

Clean out tap recess (and take the opportunity to do a barrel clean now as well)...and if fussy you could cover the tapered part of the tap with marker pen and replace, rotate a few times in the same arc as when loading the gun whilst maintaining pressure, then pull out and inspect, this will show high spots as shiny metal through the black in the case of a foreign object or ''picking up'' which can be stoned down.

BUT...These are hand lapped taps that operate on the principle (some say inspired by originally) of the domestic / commercial tapered gas tap, which obviously needs to be a perfectly secure fit, and are the best design (if done properly) of any of the tap loaders out there and light years ahead quality and function wise of the parallel later ones which were introduced due to cost restraints.

Don't be scared of the thing, it's a glorified bike pump, have a play and you will get far more out of it than getting someone else to do these very basic tasks."

<u>Aubrey</u> said: "Many years ago I successfully sealed a leaking tap on a Webley mk3 which had been ill treated by a previous owner. There were quite obvious small scratches and gouges on the outer surface of the tap presumably from mis-treatment or poor maintenance from a previous owner..
It was achieved by an electrolysis technique (electro-deposition) - applying a very thin coating of copper to the tap body, re-fitting repeatedly turning tap in tap chamber thus filling in the deformities on the tap surface resulting in a close mating fit and no air leakage.
This was done when I was working- now long retired - and had access to the chemi-lab at work. After thorough cleaning and de-greasing the tap was initially masked off to protect areas of tap where copper should not be deposited ie the tap lever, far end of tap remote from lever and plug bore hole with close fitting rubber bung.
The process was to make up a solution of copper sulphate (CuSO4) in a glass beaker, attach a copper wire to the tap by firmly twisting it for good electrical contact and attach other end of wire to the negative terminal of a battery. Then attach a small chunk of scrap copper to another short length of copper wire and connect to positive terminal of same battery. When this connection is made copper from the scrap will be deposited on the tap surface.
Lower the scrap copper on its wire into the solution and then carefully lower the tap into the solution and after a period of time copper will be seen to be deposited on the un-masked surface.
Remove tap and rinse thoroughly and wipe dry.
Thickness of coating will depend on battery current and process time. A very thin deposit is all that is required - sufficient to fill in surface blemishes and compensation for excessive surface wear. It can be done at home if you can obtain some copper sulphate crystals and distilled water and any battery will do. In the absence of suitable masking material the tap lever will need to be held clear of the surface of the solution.
This is a cheap solution to renovate an otherwise useable rifle and revive its original power. The only downside is the rather obvious traces of copper filling the gouges and on the tap surface.
If you are feeling brave and can locate some copper sulphate then give it a try. At the time of carrying out this process I was unaware of the possibility of using chain lube."

To which <u>John G</u> replied: "This is a great idea for a permanent solution, especially as copper is so malleable and will adapt to any irregularities on the tap surface. I have used a similar technique to build up worn threads and fill pits on gun metalwork, but plating with iron rather than copper. A bit trickier but very effective."

<u>Mick</u> reported that he once read that BSA used [Kilopoise high-viscosity damping grease] on loading taps :-

<a href="http://www.rocol.com/products/kilopoise-high-viscosity-damping-grease"> https://www.rocol.com/products/kilopoise-high-viscosity-damping-grease</a>

------------------------------

AndrewM later consulted a gunshop 'expert' who told him the following:

"1 Lubricant: He said there was no need to introduce Weboil or any equivalent these days, into an air chamber, as all oils create dieseling to some degree. He gave me a small tube of 100% pure silicone oil (core-rc.com), actually used for the car racing business (and expensive at £15 for 60mls). Some three to five drops were to be introduced after every tin of pellets. I wonder if anyone would like to comment?

2 Leaking tap loader: he said a new tap would be expensive to buy and fit. A better alternative, he said, which will work as well, is to dismantle the tap, place tissue in the centre hole, and spray on an aerosol external chain lube, then restore the tap to its position. This lube sticks to the surface - as it would to a chain saw, and will seal the gaps 100%. As an afterthought, however, it then occurred to me that it might also seal off a section of the air from the chamber if the tap-loader rubs against the exit hole from the air chamber. I might call him next week to seek further advice on that.

3 He also mentioned that it was good practice to fire the rifle with the tap loader in the upright position as it helped to mould the piston seal to the end of the chamber."

<u>Eddie</u> responded: "1...Do not use silicon oil anywhere where it will leach onto parts and cause metal to metal contact, as it will if put into the chamber...just google silicon oil metal to metal, it is a plastic lubricant and exactly the WRONG stuff to use! (and I have been in F1 racing and aviation at the pointy end since the mid 90's so am well up on exotic lubes).

2...Total rubbish...and may even be unneeded if you follow my earlier advice you may not need to do this if you have checked the originality / fit as described.

3...I have heard of this back in the early days of ptfe washer replacements, but not for leather....You are not moulding the end of the washer, you are concerned with the sliding fit / air seal I would say not slamming the piston into the cylinder end (which is what will happen if you DO have a leaky tap...This will wreck the washer screw...believe me I have repaired enough over the years.

All the above IMHO, as I have said your gun may be fine and just need 1/2 and a fiddle to establish the problem...Have you tried various pellets to establish the 8 pound output as various types can make over 1 pound difference, happy to send you a few original Wasps and FTT's to get a benchmark as normally these are the ones that perform the best through the chrono."

------------------------------

With thanks to Mark on the BBS for this tap-loading leak checking advice. It could be applied to any tap loader:

 John G added:

"All good suggestions. Another method which I have used to good effect in detecting leaks is to use icing sugar, heavily dusted over the suspect area. With the air outlet sealed (for example with the tap closed, or if the gun doesn't have a tap, with the barrel sealed) the gun is fired and you will get a cloud of powder from the leaking area.
I use icing sugar rather than talc or other fine powders as it is harmless to breath in, and you can clean it off the gun with a quick wipe with a damp cloth."

Eddie on tuning vintage BSAs

I have messed with a few of these, even going as far as a full button / delrin / guide job

However, this was on an old CS that was comestically poor....It did result in a super smooth consistant gun, but was quite destructive due to the machining on the trigger block.

On my other shooting guns, the normal spinger things to do can be found all over the internet, but my usual approach which may not increase power past the design limitations, but will make the gun 100% nicer and smoother in operation are to;

Strip gun into pieces.. check transfer port for damage / burrs, and cylinder for scoring. A good way to remove light marks is to use a length of slotted broom handle with wet and dry paper and a spot of light oil...I have access to lathes so would hold the cylinder this way, but if you have not then you will need to reduce the wood to fit a drill or similar.

In extreme cases you can use a sprung loaded hone (like they sell for reconditioning brake cylinders, and then finish with the paper). Be warned...you are removing material by the above, so don't attempt this unless the scores are bad enough to impair the piston sealing!

You can then use cloth and metal polish on the handle to finish. Obviously now you have abrasive particles everywhere, so a thorough clean is needed....hot soapy water, followed by mek or brake cleaner, and oil lightly everwhere asap.

Next is give the barrel a good look and clean, and check the muzzle crown closely....there are several good videos on youtube on how to reclaim a damaged crown...this is the most important part of the barrel, and the slightest damage will reduce accuracy dramatically.

Next the piston...deburr the cocking slot, and polish the two bearing surfaces that bear on the cylinder (hold the piston rod in a battery drill and use wet and dry up to 800 grit, then polish to mirror).

If possible, square off the spring ends perfectly, and mirror polish these, and also the end of the trigger block. (double springs give a smoother gun). I actually mirror polish all the outside of the spring as well, and remove the piston rod and polish the inside of the piston (but I am slightly mad!).

Basically...anything that slides against anything will benefit from this, and reduce friction. Trigger action....the let off and action can be improved by stoning and polishing sear and piston rod...I am not going to recommend this unless you are 100% confident and have the right gear, as it is very easy to end up with damage if you go a tiny bit wrong...but have a close look at the piston rod notch, and all trigger parts for cracks or burrs and remove with a fine waterstone if possible.

You can also polish the bearing screws of the trigger and sear, and also the rounded pin on the sear spring if a later gun.

That's it really apart from lube...You have now spent maybe 10 times more time on your gun than the factory could afford to in attention to detail. I use Abby LT2 grease on the main spring (ends as well!) and piston, just a light wipe will suffice. And a drop on all bearing screws and on the sear button.

Hope all this helps, this is only my personal approach and many people have their own favorite lubes / systems... but this way the internals stay original (but shiny) and it has transformed the shooting performance on the guns I have done this to. A 45 inch gun in .22 should run at 580 fps and quietly and smooth with the above. ------------------------------

Lakey/Eddie on chequering, bolt covers etc 

Q. prewar: "Its a shame no one makes replacement stocks, I thought about asking the chap who makes the nice wooden webley grips & sells them on ebay...?"

Lakey:

I too have thought about replacement stocks however I prefer my stocks to look a bit old. I like to see a few dents and marks on a stock as I think that helps to give the gun character. I would be very suspicious of any gun looking too good.

In principle, anyone with a copy lathe could turn out the same stock shapes, however reproducing the fine hand chequering on the pre-war stocks wouldnt be easy, and even harder would be the heat immpressed chequering style of the later stocks.

I have tried many times with my very limited woodworking skills to reproduce an accurately profiled wooden butt plug for the stock bolt opening. So far I have failed. The grooves on the plug are curved slightly and follow the grooves in the main stock precisely. Reproducing these is a nightmare. I think that is the main reason why John Knibbs doesnt supply a ready carved one, he only supplies the unmarked blanks.

One thing I do have is a couple of old write-off stocks which I use for any replacement bits of wood for repairing other stocks etc. That way I hope to match up the colour and character of the (French??) Walnut used on the older BSA stocks. I would recommend that to all collectors,who occasionally need to repair original stocks.

Eddie:

I did some work a while ago looking into making new stocks, but went the route of contacting a couple of stock makers who normally re-stock best shotguns and the like. Their main concern was the accurate drilling of the bolt hole/recess on straight hand stocks especially. I wanted a straight hand one with exhibition grade walnut for a project, but was looking at a cost of £6-800!!!!

Of course this was for a hand made, hand chequered fine quality one, as you rightly say, a copy machine is the way to go here!

The chequering is not as hard as you would imagine given practise, and tools are readily available on-line. I would urge anyone to try with some scrap wood, and you will be surprised at the results given a little practise.

Regarding the wood used on earlier guns, I understood it was Italian walnut in the main, this may also explain the later sile sourcing on post WW2 guns (an Italian company).

And regarding the bolt cover in the butt....I am convinced after trying several swaps that these were fitted first and the grooves and profile shaped afterwards, as they never fit exactly on another gun when swapped, normally close, but when you have seen a few totally original guns, a swapped part really stands out.

I normally shape the blank to fit the aperture and screw in place , then shape the protruding portion to match the rest of the butt area, being as careful as possible not to disturb the original finish...I use successive reducing grades of glass paper on a block.

Once the blank is the right shape, you can then start to do the grooves....using the originals as a guide, I use a needle file with one side ground "safe"...ie. only cutting on one side to do one edge of the grove at once...If you have a steady hand, you can use a piece of hacksaw blade (32 t.p.i. cuts smoother) to start off.

I then reverse the direction of filing to cut the other side of the groove....normally the original grooves are a bit clogged up with detritus, so I scrub these out with a stiff nail brush before starting.

It is nearly always the case that you will "catch" the original grooves a tad, and disturb the finish, but normally a wipe over with a minimal amount of stain on the whole area blends all in nicely.

These small bungs are often damaged by attempts to pry out, the original diaphragm spring, even when present, often has 'set" and lost some tension, or is prevented from working as intended by swelling of the wood / dirt in the joint.

It is important that the bung is withdrawn as evenly as possible to minimise damage, and the easiest way is to use two slightly larger screws than BSA use, and a strip of metal with two holes drilled in can be knocked up in seconds to provide a grip between these to allow a straight pull out.

In one extreme case I resorted to using a small slide hammer attached to the strip, again an easy thing to make, but it removed a bung that was practically sealed with varnish without any damage!

regards, Ed

------------------------------<p>

Eddie on straightening screws

Q. How to straighten a damaged windage screw on a no.21 peep sight?

Eddie:

The windage screw looks to have had a heavy hit at some stage, and an attempt with pliers or similar to move it has damaged the knurling. It is real hard to advise from a photo, but one course of action which I myself would try looking at it may be the following;

1....Remove the sight from the gun, and remove the spring to avoid heat softening.

2....Bolt the sight securely to a block of steel or aluminium (use 8 or 10-32 countersunk screws, which ever is the nearest as these are easy to get for you (ace hardware or similar etc.)...you can use nuts rather than thread the block.

3....Rotate the screw if possible so the head is bent down and clamp the block securely in a vise.

4....You will need a concentrated heat source, oxy acetylene with a number 2 nozzle, or one of those butane mini torches should do it....bear in mind that the heat may discolour the bluing on the sight if you do this.

5...quickly and carefully apply heat to the area between the head of the screw and the sight body side, and use either a tapered pry or aluminium wedge to lever the head till it is 90 degrees to the block face.....this may not be perfect, but will normally relieve the strain on the "tight" side of the bent shaft to allow removal and inspection, and the possibility of a better attempt at straightening.

6...Do not attempt removal until all is cooled down, and use plus gas, or even better mouse milk before moving....apply these while part is still fairly hot to the touch as this will aid capillary action and draw the oil right through.

7...You could also do this with the screw bent upward, and use a small brass hammer carefully with light taps, but the part must be hot to minimise the chances of breakage...the fact that it has bent rather than snapped already, shows that it is not a really high tensile part, or in a state of hardness.

Sorry if this all sounds complicated, but it is quite easy to do if you are confident....alternatively you could remove the sight and take it to a local gunsmith where I am sure you will get advice / help, just make sure they are aware that the sight is over 100 years old, and worth maybe $150+ !!

------------------------------<p>

Eddie on trigger guard screws 

The trigger guard screws.....This area is the one weak point of design on all half stocked rifles, not just BSA's, I have given up counting how many times I have been handed / shown vintage BSA's that have loose screws in this area from lack of maintenance. When I was a nipper, every gun would come with a booklet explaining the need to check all screws frequently, or better every time the gun is used.

(I am talking above about guns in otherwise good condition, just badly maintained...ie, the screw threads are fine, but the owners don't realise what a hammering spring guns give their fasteners).

There are guns out there (and shown in books) where there is a third screw (larger countersunk) through the top of the cylinder into the threaded portion of the trigger block, I don't know if BSA experimented with doing this, or whether it was a fix for "loose" guns though.

Anyway, I cannot emphasise this enough, shooting a gun, even a few times with screws loose will cause problems, which quickly can become serious!

The cylinder to trigger block fit is also affected by bad maintenance, so it is common to see guns with this part loose as well (on little used guns this fit is very good).

I have seen PTFE tape used on the cylinder threads to help stabilise this joint, and myself have used locktite on one particularly bad example I re-built (not to be done lightly, as needs careful application of heat to undo, but the gun was otherwise good, and was all new inside, so worth saving.

Remedy......once stripped, a fairly good repair for the home gunsmith is to open up the threads to 2ba size, use a 3.9 or 4mm drill, and preferable a quality 3 tap set to get full thread form.

The problem then is that screws have set sizes for proportions regarding the head against the thread so although 2ba slotted cheese head screws are easy to find, you may need to reduce the diameter of the head (at home I use a drill in a vise, and a fine flat file to rough shape, then emery on a block to finish profile screws...also works well on damaged screws as you get the same effect as new ones if carefully done).

Eddie (and others) on piston washer screws

Q. "I bought a new leather piston washer assembly including screw from John Knibbs, but the screw head when the new washer and metal cup washer were fitted tightly to the piston sat proud of the new cup washer, so much so that damage to the transfer port would have ensued had I fired the gun.

I also felt that the screw provided had insufficient length of thread once fitted through the new assembly to hold it securely. Any suggestions will be gratefully recieved.

Eddie:

You will struggle to find an alternative supply, but the screws he sells are the same as originally fitted length wise, I have used his washer kits, and you do need to tighten the screw very firmly to get the head down flush...that said, other screws I have bought have varied somewhat in head height when measured (they are done on a small run batch basis, so this may explain it).

I have also increased the depth of the countersink forming in the leather, and skimmed the screw head on one set I used when I felt that I had applied maximum torque to the screw, and it was still slightly proud.

The washer material, being leather is organic, and so will vary dimensionally somewhat. I do have low range torque screwdrivers and wrenches, so at some point will measure to failure point a washer screw to give an idea of the figures...

Once a screw or bolt has gone into a component for say 1 1/2 to 2 times it's diameter length wise, it is as secure as one 10 times the length, the problems normally start either when washers degrade or shrink, exposing the screw head to impact, or the screws themselves work loose, or have not been tightened sufficiently.

I don't have a torque figue for these, but they need to be very firmly done up, and loctite 242 used (a good grade to prevent movement, but allowing removal without heat). I see a lot of pistons with thread damage due to the age of these guns, and if the piston rod female thread is not in top condition, replacing a screw on a gun that will be used regularly is asking for future trouble.

The screw should have no lateral movement at all on testing the fit. It is an easy job however to reclaim the thread by tapping to a slightly larger, more easily sourced threadform, and this has been covered at some length here.

I know that in some respects this modification makes the gun "non-original", but personally I only own guns that I shoot on a regular basis, and that I know are in tip top mechanical condition, even if it means repairing with modern alternatives. Just some ideas as always nice to have options,

--------------------------------------------------------------------

Another question and answer in relation to piston screws was:

Q. Can anyone please tell me what the thread is of the piston seal screw on a 177 standard of 190? vintage? My local fasteners supplier thinks it's BSF but I would like to be sure.

Eddie responded:

The original BSA thread forms (and fasteners) on many screws on these guns were made in house, using machinery that made fasteners for the BSA cycles of the time....there is some debate as to whether the TPI is purely designed in for engineering purposes, or (as BSA were so good at), they made them specifically to the otto cycle thread pattern to prevent owners from buying any old screw from their local hardware / engineering source!, thus protecting their product.

I would imagine the former myself, they had the tooling already, and the fine threadform is very secure in places where the depth is shallow (keeper screws etc. for security, elevation wheels for fine adjustment).

It is not a BA thread, they are 0.1850 dia x 31.4 TPI......although as I recall the piston screw is similar to the trigger guard one in size, and a good fix for bad trigger guards is to tap out to 2 BA (you will normally have to reduce the diameter of the head of the 2 ba screw as well to fit the recess in the cast guards....although you will not get a 100% full thread with this method.....

I normally go larger and metric if I encounter a damage piston rod thread (quite common after the washer unit has worn/failed.

ATB, Ed

---------------------------------------------------------------------

Vic Thompson said this in answer to a query about the piston washer bolt in a 1935 BSA breakdown pattern air rifle:

According to A BSA drawing for that part it is 0.1656" dia, 37 TPI and 0.476" to 0.480" long over the threaded part.

The head is "cheese head" with radius on the underside of diameter 0.373" to 0.377" with a slot width of 0.040" to 0.045", 0.050" to 0.055" deep.

The head is 0.095" to 0.100" deep.

The screw has a short radiussed shank. It fits into a brass cup washer etc. ----------------------------------------------------------------------

On the general subject of threads, without having the info supplied above by Vic, David9d said:

From my experience of messing about with vintage motorcycles and vintage air rifles and model engineering, here are my thoughts on the thread sizes.

When your BSA Break Barrel was in production the only metric things around were the spark plugs in engines, and the American system was almost unheard of. So I would expect your screw to have been either Whitworth or BSF, with BA as an outside possibility.

You say that M4 is a loose fit, but the Threads per inch (TPI) must be close if it screws in.

OK, now a few comparisons ,from my vintage Engineers Tables:- M4 is 0.157 x 36.3 TPI (Fine) or 0.157 x 33.9 TPI (Coarse) 8-32 is 0.164 x 32 8-36 is 0.164 x 36 3BA is 0.161 x 34.84 5/32 Whit is 0.156 x 32 3/16 BSF is 0.187 x 32 I would guess that the original was Whit or BSF, so 32 tpi is a good starter.

As M4 is a loose fit it is looking like 3/16 BSF should fit, certainly would if you ran a tap through it first. When you re-assemble clean any oil from the screw threads first and give them a dab of Loctite (or Evo Stick if that's all you have ) Another thought, as it is an internal part and well out of sight, consider re-tapping to the next size up, say M5.

Happy shooting

David

------------------------------

A final contribution on this subject from John (Dogfox), who says:

"Regarding the threads used on the early BSA's, after much research and delving into old thread tables I believe them to be the long obsolete "Enfield" threads, which I think may even have been in use before the Whitworth form was standardised.

For replacing the trigger guard and loading tap retaining plate screws, nominally .1656 x 37 tpi, an M4 x.7 will screw staight in but is far too loose. I make replacement screws by turning about .006" to .008" oversize for an M4 (nom .157") and screwcutting at .7mm ( pitch if only a metric gearbox is available ).

I find this works very well. If the piston retaining screw is the same thread ( dunno? ) this will work on that too, unless the female part has suffered damage in which case re - tapping to a larger size is the way to go.

Hope this helps,

John.

Lakey on accuracy, barrel cleaning and re-lube

I would say that accuracy potential from a BSA Standard should be in the range of 10 yds - 0.5-1.5" groups , 20 yds - 1.5- 2" , 25 yds - 2-2.5" (rested). I have shot 3-3.5" groups rested out to 50 yds with a .22 Standard before now, however you have to find the right pellet combination for your gun.

The other night, down the local range I was struggling to put in 2.5" groups at 25 yds, with one of my .22 standards and Milbro pellets, however when I changed to Old Eley Wasps the group size went down to 1.5" straight away.

One tip - Make sure you clean the barrel really well, as even though they may look clean, the gun might have lead fouling in the barrel (built up over the years) which will have some affect on accuracy. I have always found some accuracy improvement after a good barrel clean.

To be honest barrel cleaning is just the tip of the iceberg.

Whenever I get a new BSA, I like to give the gun a thorough going over to establish the gun's exact condition (both inside and out) and the gun's suitability for shooting.

Usually, the gun in question hasn't had any maintenance for years and is in urgent need of a relube at the very least.

First step is to strip the gun down, and clean all parts - this involves often going over the outside of the gun with 0000 grade steel wool and light machine oil, to remove any 'active' external corrosion. I also often resort to a sugar soap solution applied to the stock with a tooth brush - especially around the chequering, then the stock is rinsed and dried.

I dismantle the trigger mechanism and de-gunk that before re-assembly and LIGHT oiling. The I turn my attention to the spring and piston unit, de-gunking and then checking all components.

At this stage I often replace the leather piston washer assembly and thoroughly check the spring and inside of the cylinder.

It is at this point that I view and check the barrel/rifling and clean if necessary. I use a phosphor bronze brush on a long cleaning rod - introduced though the cylinder so as not to damage the crown.

I use Parker hale 009 to remove grot in the barrel and then keep cleaning the barrel until I am satisfied there is no more dirt up there, then I use a pull through with a small bit of rag and light oil to put a film into the bore. If there is active rust present in the barrel I very occasionally use fine steel wool round a jag to loosen it before the phosphor bronze brush is used.

Finally the gun is reassembled with a smear of moly grease on the spring/guide and a thin coating of 3 in 1 oil on the piston washer.

Once I have done that I know I can use the gun with confidence for years to come.

ATB

Lakey

------------------------------<p>

Eddie on piston washer lubrication/ re-sizing

No matter where where you go for info, you will get many conflicting ideas about the fitting of leather washers!....I personally do mine the way they 'used to' when the guns were made, The subject of lubrication is also something that people will never agree on....

I know people that use all sorts of oils, even neatsfoot, now the theory is that you must keep the leather supple, And there is also a theory by Cardew, which is still argued over, that older guns run on a very slight diesel action.

All I know is that in the 60's, all guns with leather washers had a booklet that said to put one or two drops of oil into the cylinder every 1000 shots or so. So.....On my guns, which when settled down (2 tins or so of pellets) give consistent velocity's within 10-15 fps, this is what I personally do;

Fit the washer dry, using a couple of drops of loctite on the screw thread, then in a lathe, or using a cordless drill, holding on the piston rod, use glass paper to size the washer till it is an easy sliding fit in the cylinder.

Here is a picture of one done;

Assemble gun with a wipe of moly on the two piston bearing surfaces, and the spring. I use Cengar green oil; http://www.cengar.co.uk/pages/e-green-oil.html And open the loading tap, fill this with oil.....close the tap, and stand gun upright for 48 hours to allow to soak washer, work the action several times before use....you will get a little smoke and possibly dieseling on the first couple of shots (especially on 45 inch guns), but then all should settle down.

The original oil that Webley sold to use on their spring guns was a straight 30 weight oil, so another good one to use is Silkolene chatsworth 30 or a similar 'classic' oil.

Q. Barryeye: This may be a silly question but if the washer is a little on the tight side when new, wouldn't wear and use make it the perfect size in time?

Eddie:

This is correct, the gun will just take much longer to settle down to maximum efficiency if the washer is tight, as well as putting extra strain on the securing screw (in extreme cases). I normally size mine (the Knibbs replacement ones are quite substantially oversize), so they are an easy sliding fit in the cylinder ie. dry they will drop slowly down under their own weight.

I have bought guns that have been "overhauled" in the past, and being a fussy so and so always check them over before I use them. In at least two cases the piston was so tight in the bore because the washer was new and oversized.

It was quite a physical effort to get the unit out by hand.... obviously when cocking the leverage hides this friction somewhat, but the drag effect on the securing screw (which is quite small in size) had caused one to loosen!

------------------------------

Eddie (and others) on BSA thread form and reclaiming

Eddie:

The original BSA thread forms (and fasteners) on many screws on these guns were made in house, using machinery that made fasteners for the BSA cycles of the time....there is some debate as to whether the TPI is purely designed in for engineering purposes, or (as BSA were so good at), they made them specifically to the otto cycle thread pattern to prevent owners from buying any old screw from their local hardware / engineering source!, thus protecting their product.

I would imagine the former myself; they had the tooling already, and the fine threadform is very secure in places where the depth is shallow (keeper screws etc. for security, elevation wheels for fine adjustment).

It is not a BA thread, they are 0.1850 dia x 31.4 TPI......although as I recall the piston screw is similar to the trigger guard one in size, and a good fix for bad trigger guards is to tap out to 2 BA (you will normally have to reduce the diameter of the head of the 2 BA screw as well to fit the recess in the cast guards....although you will not get a 100% full thread with this method.....I normally go larger and metric if I encounter a damage piston rod thread (quite common after the washer unit has worn/failed.

<i>Q. Peter: Thanks for that. I was going on information given to me by Chambers. When they supply a new piston seal and screw they use 2BA! You say you go bigger and metric! This to me means going to M5. Is this safe? there isn't a lot of rod left after drilling out for this.</i>

A. Eddie:

5mm is possible and works, as the existing screw O.D. is around 4.16/4.2mm, and the drill size for tapping 5mm is 4.2mm....the piston rod is 9.2 in diameter and engages full thread for normally 3/4 of an inch into the piston, so you will have 2.1mm of material all around the new screw (granted this is threaded, so the 2.1 is to the tip of the thread, but it essentially a solid mass, and can be treated as such.

If you want to err a little smaller, you can also use a 10-32 UNF tap, which is the one I usually use (better tpi), but I was not sure if you had access, plus you may not get 100% full thread with this latter size (I always use loctite 242).

I have never had a problem with 10-32 UNF repairs, and to be honest, a 85-95% finished thread is far better than what normally was in the gun before repair.

The piston rod is drilled 0.375 deep normally by BSA themselves, and I use a 3 tap set (first, second, bottom) to get a full thread all the way down.

The tapping drill for 10-32 is a number drill, number 21 (4.038mm), so as you can see it will remove most of, but not 100% of the existing thread.

John (Dogfox) said:

"Regarding the threads used on the early BSA's, after much research and delving into old thread tables I believe them to be the long obsolete "Enfield" threads, which I think may even have been in use before the Whitworth form was standardised.
For replacing the trigger guard and loading tap retaining plate screws, nominally
.1656 x 37 tpi, an M4 x.7 will screw staight in but is far too loose. I make replacement screws by turning about .006" to .008" oversize for an M4 (nom .157") and screwcutting at .7mm ( pitch if only a metric gearbox is available ). I find this works very well.
If the piston retaining screw is the same thread ( dunno? ) this will work on that too, unless the female part has suffered damage in which case re - tapping to a larger size is the way to go.
Hope this helps,
John.

Re. a question about trigger guard screws, John G said this:

"I have just dug out my 1906 Improved Model D, and yes I found that a 3BA screw will replace the trigger guard screw OK. However it is a loose fit, which suggests that the BSA screw has the same number of threads per inch as 3BA but a slightly larger diameter. If you tighten it up enough this shouldn't be a problem."

Eddie on reducing 'twang' on firing 

You could check the fit of the spring in the piston, and wrap some thin ptfe sheet, or material from a plastic drinks bottle around the end of the spring where it fits in the piston, some people swear by thick grease, but it will mess up the firing cycle and also finds it's way eventually to the washer.

Obviously a spring guide is the answer, and the standard BSA spigot on the trigger block is normally fairly adequate on these, but it could be worth making a delrin sleeve to go over this if you have the space inside the spring.

I know these are not original parts, but both ideas are easily done, and removable!

It may also be worth removing the spring, and checking the ends are 100% square, and giving them a polish, when you re-assemble, put a smear of moly on both ends to aid spring rotation, this also can quieten down things a tad.

------------------------------<p>

Eddie on rebuilding front sights 

Note: The example done below was deliberately made bigger than standard to go with a modified rearsight blade.

Hi, your best method is to remove the sight (drift out from the left as looking down barrel and replace from the right), and use tig welding to build up the sight.

First you do a few small runs to get the blade hight somewhere close, you then shape this with a dremel and files, then you do a larger bead at the top and re-shape the bead, with practise it takes an hour or less, and the finished result is as good as the original in appearance, and better in respect that the sight blade is now slightly more malleable and will take a knock without snapping like the original casting.

Also the base is original so no re-fitting woes as you often get with pattern units! I use 0.8 mig wire as a filler, with the copper coating rubbed off with scotchbrite, an alloy steel like bostrand 41 is good, but mild steel a18 works well too. An example in various stages;

 

This one had a larger bead than original when finished, or you can make it barleycorn or any other profile offered by BSA originally.

Eddie on tightening loose sights

Just thought I would quickly say, although I am sure no-one on here would take a centre punch to a gun in this day and age (I have seen so many that have suffered this), that it is the work of seconds to securely tighten sights / other parts in dovetails. It is a waste of time doing anything with the sight in place...it must be removed before starting...from the left hand side (looking down the gun in the shooting position), and replaced from the right.

Using a small hammer, a 4 ounce or similar cross pein will do, but a repousse is better (with the face polished as well as possible...should be mirror), just gently tap the area at the the top of the dovetail to close it a tad...you can do this on a new, freshly blued gun without marking it or causing any damage if careful. This will do the trick in most cases. Degrease the dovetail and the sight base with acetone, then refit and zero gun...when zeroed, remove sight wheel / blade, and use a pin dipped in loctite 290 (penetrating) ...with the gun on it's side, apply this to the base of the sight where it meets the barrel...It will find it's own way in. wipe off any excess, wait 24 hours and you have a permanent set of stable sights.

To remove..use a heat gun gently to degrade bond, and tap out as normal.

In extreme case...buy a cheap set of feeler gauges..fit sight, then insert gauges under till sight is snug...cut gauge to match sight base (heavy scissors or non serrated snips work well)...blue with cold blue, then degrease all and proceed as above, fitting shim and base together. I have sometimes loctited the shim first and used a small G clamp with padding or shaped wood under the barrel...you then proceed as if a new dove tail.

Invest in a nylon mallet for rear sight removal, and ideally also a small plastic faced hammer...easier than using a normal hammer and hardwood / nylon drifts....remove blade and wheel before removing sight.

If purchasing a repousse type, get one that has a small radius at the hammer face edges...ie not sharp unless you are quite handy*...a lightweight panel beaters hammer can also be used with care.

*A sharp edge can mark the barrel unless you pay 100% attention.

To clean up burred screws, tap gently with a small hammer to blend back in the metal, then use a swiss file in the slot if any metal has filled it...you can gring a swiss file very thin so it only cuts on the edge, and has two "safe" sides...a bit like using a hacksaw blade with 60 tpi.

Eddie on springs, pellets and performance

See also:

https://forum.vintageairgunsgallery.com/vintage-bsa-resources/vintage-bsa-lincoln-jeffries-technical-tips-faqs-2/#post-5034

As the weather is rubbish here, I spent a bit of time in the man cave this afternoon to measure some bits / do some testing which may help. The original BSA springs I have for the 45" guns, (originals are stamped on the ends), both single and twin sets are 0.136" gauge wire x 33 coils if single, 17 coils (left and right wound) if twins.

They are a quite stiff temper and I have read that the twin springs on the larger guns were introduced as they were getting breakages back then (pre ww1) in the large single springs, and the effect of fitting twins reduced the recoil somewhat and gave a slightly smoother shooting gun, the latter I have found to be the case personally.

This was in the improved model gun era, ie. pre 1914...I am not sure what happened after WW1, I have understood that later 20's / 30's standards had large single springs from new, so maybe they had changed the tempering process / learnt something in between.

Anyway, I did some chrono testing on a late standard with 4 types of pellets, you will notice how much better the wasps are in consistency than the domes' or H+N's, and the gun shoots the most quietly and smoothly with these, it is noticeably more noisy and harsh with the FTT's, with the superdomes being in between.

The superfields were awful, dropping the power down to the mid 9's and I only fired two!

Back to springs...I quickly pulled the gun apart and had a look, it is well shot in, and the piston moves easily in the cylinder under finger pressure with the slightest drag, the spring fitted is an Airsporter one (0.127" wire x 33 coils), so the same length as an original BSA one, but thinner wire gauge.

These are good units as long as you fit either a quality pattern, or preferably an original...there was a guy selling genuine N.O.S. Airsporter springs on the Bay, they were only a tenner or so and I put a heads up on here a while back, they are top quality and worth stocking up as many replacements are simply not as good! The next photo shows 3 springs,

The top one is a N.O.S. BSA Airsporter which measures 10 1/4" overall, with a wire gauge of 0.127" x 33 coils. The second set are a set of pattern twin springs, in 0.134" wire x 17 coils, these are 10 1/8" long, and were removed from a gun as it was very harsh and over the limit!

The third set are a set of original BSA twin springs, these are 0.136" wire x 17 coils , a stiff temper, and are 9 1/4" inches overall..this gives minimal preload, and these springs give mid 11's in energy and are very smooth in operation. You will notice the striking difference in the length between the pattern and genuine twin sets, due to the more open winding...

I have several other BSA twin springs, and they are all shorter than these patterns, and more interestingly, if you measure between the gaps of the coils on both the genuine BSA Airsporter, and the genuine BSA twin sets I have, the variation is a minimal plus or minus 0.002"...ie very accurately wound...the patterns vary by up to 0.030" between coils, this must have some effect I would imagine (but don't know what) or maybe it matters not a jot, but they are not as accurately made as the genuine ones! Anyway, guns do vary but most people highly rate the wasp .22 pellets in these, and they always fetch good money when they appear for sale, the superdomes and the FTT's are both very good accuracy wise, especially at longer ranges, but many people who have never fired the period pellets in their prewar .22's would be surprised at the effect they have on the firing cycle, they just seem to suit most guns better and they shoot noticeably more quietly.

So...decent airsporter spring and superdomes seem to work well in this gun, so you are on the right track with the pellet choice you have.

Lakey's point about cleaning was something I forgot to mention, in the past I have posted about results I have had after cleaning what initially looked like a smoothbore, it was so full of crud!

Eddie adds in a different thread:

I recently acquired a little used Model B (43" gun) which shoots very well (in the low 700's with hobby pellets) and the spring was a flatwound original BSA. Spring gauge is 0.160" x 0.082 Flatwire x 40 coils.

The preload is 2" which sounds a lot, but the spring (as are most flat / oval types encountered) has a fairly soft temper / feel, so assembly is easy with little effort required, in comparison with the JK springs with a similar preload length, which are brutes!...

I have had good results in the past with flat springs from T W Chambers, the part number being MS016 which is a 40 coil as per the model B above. In a later thread still, Eddie adds; the springs are as follows...

BSA made essentially 3 sizes of Improved gun pre 1914 with the same cylinder dia, as well as a reduced dia gun called the Juvenile, they are to keep things simple determined by the compression chamber length, but it is easier (and the norm) to refer to the overall lengths of the guns which are (approx as stocks can vary) 45 inch, 43 inch and 39 1/2 (I think without reference at the mo').

So...the 45'' gun was in .22 or .25 only, the 43'' gun in .177 and .25 (both sizes of .25's are very rare!) and the shortest is the Light model.

Chambers should really list their springs by action length to be clear, and it would be worth an email to clarify which is correct, but I am 90% sure the spring pair will be correct for a 43'' gun, but you can also fit a single long spring, and in this case it is easier to shorten one rather than two if needed.

The dual, opposite wound springs were advertised to counteract torque on firing, and were standard in .177 guns, but a single spring was also used. I have shot both and the dual springs feel slightly ''softer'' on cocking, and when fitted to the longer .22 versions feel slightly different on shooting to me, but some folk say they cannot notice any difference...

and in a post responding to an Improved Model D owner complaining of disappointing power, he added:

I took both [Model] D's I have down, one has the original springs in, and the other on pulling apart had what looked like a cut down sporter single. The original twin spring gun was doing 710 fps with Webleys, and the other 685 fps with the same pellet.

I have found you two options, a pair of flat wound springs, look like older pattern jobs as no BSA marks, and one is longer than the other, but they run at 685 fps in my gun.

The other is an Airsporter (I think, all are in a box marked ''BSA''), which I cut down to match the spring in my other gun, this was giving 680 fps. Different feel and different preload, the double set has 58mm stickout, the single only 13mm.

For reference in case anyone is interested, the single spring was cut down by approx 20% of it's length and as fitted measures; 3.32mm wire gauge, 26 open coils + two 1/2 tight closed ends so 27 in all, 193mm overall length, spring O.D. 20.70mm.... ------------------------------

Martin on pre-WW1 keeper screws 

This is a nifty tip if you are missing the little keeper screw on the cocking lever pivot bolt on your pre-1914 BSA. (I hope I have understood this right and if I haven't, I'm sure Martin will correct me.)

Martin writes to say that on all pre-1914 rifles, under the piston washer there is a small locking screw. This screw will also fit the cocking lever pivot bolt's keeper screw thread.

When used on the piston, the screw holds the piston rod and prevents it from turning. But if you remove it to use as an external keeper screw, you can tap out the thread and fit a screw with a metric thread instead. Alternatively, you could use solder to lock the rod in place.

Lakey/Eddie on solving failure-to-cock  

Lakey: 

"First thing to check is that the trigger is free moving and that you have the trigger spring in position behind the trigger to provide upward pressure on the sear.
If the trigger spring isnt present, then try cocking the gun and pushing the trigger forward from behind, that should result in the sear holding back the piston.
Exceptionally, you could have a worn sear hook or a broken trigger sear, however in all my years collecting these guns I have never come across either one of these, however I guess it is possible. My money is either on a Clagged up trigger or a broken or missing trigger spring."

Eddie:

"As Lakey says, these guns have a very basic mechanism, so very rarely give problems. However, due to their age, and often many owners over the years, they often have been tampered with.

One other thing I would suggest is to back out (anti-clockwise) the trigger adjusting screw in the trigger guard if fitted. If this has been screwed right in it can result in the gun not "holding".

There is a sectional drawing which gives some idea of what is inside (although slightly different to yours as the trigger spring in the diagram is different, the piston and trigger relationship and construction themselves are very similar to yours ) elsewhere on this website;

Other potential faults could be;

1...Incorrect main spring wire gauge causing spring to become "coil-bound" before the piston rod engages.

2...Damaged ("opened up")or replacement secondary cocking arm (the piece that connects the main lever to the piston), giving insufficient piston travel.

3...Washers added behind spring,

4...Spring guide missing (tube that fits into trigger block),

5...Piston rod itself has been damaged / repaired with incorrect profile.

6...Mainspring broken (may not be obvious).

7...Trigger upper part damaged/broken.

If Lakey's suggestion about the trigger, and the trigger adjustment screw idea of mine do not help, then you should look inside. this is a simple job anyone can do,these guns come apart in a few moments, and any problem inside will be obvious (or perhaps you could put up photos).

Please be careful with the screws, and use a parallel ground, well fitting screwdriver blade, this is the only real precaution to take as original screws are quite hard in temper, and can be damaged.

Anyway;

What follows is the way BSA themselves used to put in their old booklets, and prevents damage from vise marks etc! (in fact if you read through this link, it will be described in "old fashioned" proper English);

Remove the trigger guard, and with the trigger pulled back slightly to clear the cut out in the cylinder, stand the gun vertically, muzzle down on a piece of carpet or similar to protect the end of the muzzle.

Standing up, rotate the stock and back block as one unit anti clockwise, this should unscrew...as the block is nearly out, keep some pressure on the back as the main spring will be pushing against the trigger block from the other side (not much, easy to control).

Remove mainspring.

Remove pivot screw(s) that connect the main cocking lever to the secondary lever, and use the shorter now free lever to push the piston back a bit, remove the shorter lever from the gun, and you can use this to "hook out" the piston if free.

To check cocking function of a dis-assembled gun, push the piston hard into the trigger block, and it should click as the trigger catches it, release by pulling the trigger.

(this assumes trigger spring is present, if not apply pressure on trigger from behind to simulate spring).

Any damage to the end of the piston rod, or the trigger will be obvious, but again, if unsure please put up some photos for more help."

In answer to a BBS post about an Improved Model B that would not cock, Eddie said:

Essentially the very first job is to check inside the piston to see if someone in the past has put any washers up there to try and increase preload. If not then you need to do the sums as per the above link, ie. available space from piston inside bottom to breech block face.

Next is to work out you spring height so wire dia x number of coils...This should ring alarm bells at once if even close to your initial measurement as although the springs on these compress fairly tightly, they are not normally coilbound.

The ones shown will be original BSA...if plain then they will be patterns (which have been made since for ever, so may be 100 years old themselves!) The originals twins on 43'' guns from this period are a rounded end oval / flattish wire, not round.

Looks like you are probably into removing a coil or so from at least one spring. This has been covered at great length on this forum so do a search, easy if you have a Dremel / propane torch.

Below is general stuff for anyone else who may have had this problem as a couple of other things can crop up;

CHECK IF IF THE SECONDARY COCKING LINK IS IN GOOD ORDER, AND THE PISTON SLOT HAS NOT BEEN ELONGATED,

Take note of the highlighted bit above, I have seen both reshaped / bent / bit at the end damaged arms and bad piston slots over time in repairing these, and have been caught out myself at first as I have had access to spare known good springs / pistons / trigger blocks have swapped them into non cocking guns...and have been scratching my head at why the thing still will not cock even without a spring as both the previous steal a bit of piston travel

Webely MK 3's also suffer from the cocking arm bending and subsequent loss of piston travel....Usually caused by those muppets who yank on the cocking arms like Gibbons and slam them back...I still see this on occasion when out and about, total lack of mechanical sympathy!"

Eddie on early butt plate screws and stock bolts 

Eddie wrote the following:

<b>Lincoln butt plate screws</b>: these are the same as Lee Enfield items, and there are always tons of N.O.S. Lee spares on the bay, so either possibly contact a seller, or google Lee Enfield as there are several retails / specialists of these rifles who no doubt would have a pair.

<b>Lincoln/BSA Air rifle stock bolts</b>: The Enfield bolts are the same thread (with a square section at the threaded end) and have the same dia slotted head, but are parallel shank and a different length. I bought a few cheap at an arms fair with the intention of having spares should I ever get stuck, but they will need cutting and welding to work on an air rifle.

The lee Enfield stock bolts are in fact waisted in the shank, but less so than the original. They are 33mm shorter, so could be used as they come if the stock counter bore was deepened (check no washer inside if doing this!).

I believe the original BSA air rifle bolts were "modified" from the existing Lee items... It could be they were "drawn" longer, this would explain the more pronounced waist, which if you look at the photo, does indeed look like the BSA bolt is a "stretched" version of the Lee item.

The other option is to weld in an extension section.

You will notice a square section "extension" on the thread, this can easily be removed leaving a good amount of thread - in fact one more turn on the example I have compared it with (Imp Mod D).

Bsa Air Rifle and Lee Enfield bolts compared:

Eddie on the power potential of vintage BSAs 

Eddie says this:

The information below is based on my testing guns over the years, It is a guide only but hopefully will come in handy.

Generally three lengths are commonly found (there are rarer junior guns and shorter .25s but these are rare, So below are the normally encountered).

Light / Ladies at around 39" long, only in .177 and a good one will be at least 600fps, with some higher using original springs, these will make more power with cut down stiffer springs but are not so pleasant to shoot.

Pre 1918, Standard length Lincoln's / Improved B's / Improved D's and the same sized (43") later 1919-39 43" CS prefix guns and the rarer Club No. 4 "C" prefix models. These can go up to 725 fps if fresh inside, again 99% are in .177. I have seen 720fps / 8 ft pounds from a real sleeper in perfect order with original springs and washer, but they are a one in a thousand find. 

45" Guns...pre 1919 known as the Sporting model or at the end of it's production the Standard model (.22 / .25) then again from 1919-39 as standard no2 (.22) or C.S. / Club Special / Club Standard (.177).

These long guns can be full power, with the earlier Sporting .22 normally making high 10's to full power and even slightly over (up to 600fps and beyond in .22!)

The 1919-39 45" .22 guns (S and T prefix) usually had a different piston / rod and these seem to top out at 560-70 I have found.

The 1919-39 45" .177 guns (These are CS prefix )can go up to very high 700's in fps.

I have omitted some rarer guns found, and been simplistic but the above is a basic guide. I have used FPS and these figures are using fairly light waisted pellets as would have been available originally.

Bear in mind these figures are for either little used, or rebuilt and run-in guns in good order, these guns are all getting older now, and although built to a very high standard originally, may have had generations of neglect and abuse, so always chrono/ test fire for accuracy any example you are intent on using to see how it shoots. They do vary and some which have had all sorts down the barrel may not be accurate."

Eddie also says about the Light Pattern:

"If resealed with leather they will climb up a bit, normally 525 - 550 is what I have seen from ones I have tested, with near 600 from one I rebuilt that was in good order after a couple of tins (these figures are with hobbys / R10's which are quite light but are great at garden ranges and very accurate normally).

I have found that with a fairly light but draggy fit on the seal before oiling, they need a couple of tins through them to really settle down (I build mine dry and oil afterwards with mineral oil as per original. I know neatsfoot and other oils are recommended but I have never had a problem doing this with lower powered guns)."

On a similar subject, a poster on the Airgunbbs.com called POLO writes this about the Improved Mod D Light Pattern:

"Many years ago I had my BSA refreshed by Gerald Cardew who in those days, 1981, was the man. I found the Test Certificate the other day. The results were with:

BSA Pylarm an average of 712 ft/sec. 8.2 ft/lbs

Hobby an average of 641ft/sec. 6.4 ft/lbs.

The energy available from the spring was 33.1 ft/lbs which equated to 24.7% efficiency. As I recall the spring was a cut down Original 35."

On a thread about an under-powered late 1930s 45in rifle, Eddie said:

Looking at the simplified pivot on the cocking arm, this is a late gun which will have the extended skirt patent piston, I have found these top out in the high 10's compared to the earlier 45 guns which can go full power, the later guns have a smaller swept volume as per this photo as the latch rod is slightly longer (45 inch sporting is second from bottom).

Pellet wise, you could try superdomes out of the modern ones or Hobbies even, they do tend to like "shorter" pellets I have found, obviously Wasps and Webleys are getting hard to find now, FTT's in 5.54 worked well in one of mine, another did not like them, so a case of experimenting.

As for the oil I use air tool oil and shoot the first shots slowly to allow the excess to disperse and avoid dieseling, that's my preference, others have their own personal opinion, I just grew up with mineral oils and if used sparingly they are fine for me anyhow.

Piston sizing and max power with leather seals will occur after 500-1000 shots of running in, you can speed this up by sanding the dry piston a bit as mentioned so it is a light sliding fit.

Leather seals take some patience, we have all become accustomed to modern synthectic ones that are pretty much at perfect performance if sized correctly 

On the airgunbbs.com, slug-gun (a very knowledgeable collector) adds: "The Standards were not 'designed' to produce any particular foot poundage, certainly not 11 - 12 ft lbs as such. that limit was not introduced until 1968 I believe. They were designed to be powerful however and a new rifle could produce far in excess of the current 12 ft lb limit.

I have seen such give a consistent 700 fps with 14.4 g Eley Wasp over a Skan chrono, no dieseling, with a 12 fps consistency... The Standard in question was little used and original, and the gunshop where it was tested/owned, removed the mainspring which turned out to be the original 2 part item!

Anecdotal evidence also suggests that these great old rifles would easily outshoot a modern gun limited to 11 - 12 ft lbs, back in their day."

Eddie on Improved Model D pellet choice 

Pellet wise in mine I have found they prefer lighter types, so Hobbys and similar match types go very well. The AA fields can be accurate in some, but can be harsh feeling and drop power. I test all pellets both for accuracy and power / smoothness of shooting, and in the .177 guns I have I prefer to use older pellets such as pylarm / wasp / webley GP (all essentially the same pellet). These are all out of production but easily available on that auction site, and because there is so much choice of .177 out there, tend to sell for not silly money...

[If] you have a chrono, see if they help. A really fresh tight 43" gun running well will shoot at 740 fps with a wasp or similar weight pellet, most should exceed 600 fps easily.

Replica mod 21A peep sight project 

Thanks to Jules for these images:

Eddie on lubricating a vintage B.S.A air rifle 

Q. I have just become the proud owner of a 1930s Club Standard. Reading some of the original manuals, they suggest regularly pouring oil into the cylinder via the loading tap. Has anyone out there got any advice on this please?

Eddie's answer:

To start, there is a huge range of differing opinion on this subject, many will advocate using Silicon oil (No!), or neatsfoot oil or others which are resistant to detonation, and still perform the job of keeping the piston sealing washer supple.

The reason is that that spring guns, if over-oiled with any combustible type of oil will diesel, ie. detonate the atomised oil in the chamber, which can in extreme case cause serious damage.

This phenomenon is increased with the power of the gun, and rapidity of firing besides quantity of oil/grease present.

I can only advise on what I do personally, and what works for me!

The original BSA advice of filling the tap and firing to oil the bore is obsolete and should not be done. However, when building a gun with a new washer, I DO fill the tap, and stand the gun upright for several days before use. Often you do not get dieseling by the simple precaution of firing one shot, then waiting a few seconds (a min or so) to allow any atomised oil to settle before shooting again. After 20-30 shots the gun is normally clear of excess, and the bore can be pulled trough and the gun shot in (at least 500 shots to bed in a new washer I have found).

Once all is settled, I then put 2-3 drops of oil in the tap every tin of pellets or so, or annually on little used guns, and then fire 10-20 pellets slowly to clear the excess.

This is my personal regime, based on instructions you used to get with new BSA's in the 1960's / 70's, and it works for me.

The oil supplied by BSA and Webley was a straight 30 weight normal mineral oil. If you want an exact match several companies that do classic motor oils make this, or I have fund that air tool oil works well, especially one by Cengar, which is green in colour.

So basically, oil judiciously and sparingly, and shoot slowly and carefully afterwards. If you do get a "bang" (a loud report with smoke emitting from the muzzle), do not shoot again for a good few minutes!

I use this system on my most powerful BSA's (45" sporting .22's giving near 12 foot pounds) without any problems, and they are very good shooting rifles with shot to shot consistency in velocity equal or better than anything you can buy new.

ATB, ED

He adds:

just another thought...If the gun is new to you I would strongly advise inspecting the piston / spring etc. for two reasons.

One is general wear and tear / foreign objects etc. These guns are very well made and can seemingly function well despite suffering damage, so a visual check on the security of the washer, and in the chamber for any odd itemsis a must when you obtain any gun you do not know the history of.

(The transfer port on these is large, and if the gun has been loaded BEFORE being cocked it is possible to suck a pellet back into the compression chamber...This is more common than you would imagine)

This stripping down in turn allows you to degrease and lube properly (It may well be that the previous owner had done this, but always worth checking).

The first thing I do when I look at a new gun is look in the cocking slot at the state of the spring...if lathered with grease it comes apart at once, as over greasing can also cause detonation as the grease is flung forward with every shot and migrates to the washer / compression area.

Deburr any obvious marks on the piston, and the spring ends, If lathered (or Dry!) degrease the cylinder / piston (including inside) and spring, and all it needs is a light wipe of a high moly content grease on the two bearing surfaces of the piston, and a light wipe on the spring(s).

I normally wear a pair of nitrile gloves, and put a small dollop of grease in one palm, then with a hand washing motion spread it over both hands, and then simply rub over the spring. I also put a tad more on each spring end, and a wipe on the bearing surface of the trigger block where the spring touches. That's all it needs to work well for a year or two of regular use.

Eddie on BSA/Lincoln factory inspection marks

All prewar BSA /Lincoln were stamped with a plethora of inspection marks denoting various stages where they were checked by inspection at the factory.

If you pull down the cocking lever you will see loads more as this area is where most are "hidden", including the tap serial number, sometimes the rifle serial number (a duplicate of the number on the trigger block), and various others, also sears and triggers especially have often individual stamps (a stylized star being common).

I don't think anyone has ever explained what each mark is for in anything I have read, so you will just have to accept you will never know, although you can be re-assured your gun and the components that it comprised of were checked several times on it's journey from the metal rack to dispatch!

Eddie on Light Pattern piston and spring dimensions

Piston to block when cocked:

Piston depth for spring seating:

Piston dimensions:

If your piston looks O.K. to the photos and sizes I have shown, It may be a coilbind problem, this is why I have shown the depth and piston to block sizes (in inches). If you add these together you get the available space the spring has when compressed.

You then measure the spring wire and times that by the number of coils and that gives you the compressed (to coil bind) height of the spring...If this is more than the available space obviously the gun won't cock.

Sear engagement is easily checked by just pushing the piston into the block when gun is apart.

Spring on this gun (a little used earlier ''two hole'') light pattern is for reference;

Flat / Oval wound wire 0.081" x 0.127'' x 31 coils, 0.800" O.D. X 0.508" I.D. X 7 3/4" long...The gun is high 500's so some shortening of the spring from the as new length may have occurred, but all looks very original.

Piston bore is 0.835" by the way, and piston O.D. is 1.090"

Hope this helps,

Ed

Eddie/John on double notch piston and safety sear rifles

The serial prefix "S" and the patent number 30338-10 on the block denote [a pre-WW1 rifle] fitted with a double notch piston and safety sear set up... ...these if working well, work well, but if disturbed / messed with can be a pain.

The system was quietly dropped by BSA, and also guns that "played up" were returned to the factory or dealer and had the system deactivated by way of riveting the two moving parts as shown here:

You will need to pull out your trigger group and check the springs, the group to the left in the photo (thank you Trevor from N.Z. !) shows the original design, the two springs must be in balance, and if replaced with the wrong type can be a problem.

BSA simply made the units a one piece as per the right hand photo when they played up by stopping them moving.

The original concept was an anti beartrap idea a bit like the TX200 thesedays, with the secondary notch holding the piston before the full cock position. Another issue could be a loose / damaged piston rod...

Unfortunately I have seen a lot of these with evidence of attempted fixes and filing as they have played up on previous owners, always these have been original guns without the BSA "fix" .

John Mil adds:

"Something that is not immediately apparent is the double safety sear fitted to the Junior 11 or Juvenile is smaller than the double safety sear fitted to contemporary standard air rifles. I found this out when I obtained a replacement original sear for a Juvenile and found that not just the cylinder has been reduced in size but the stock, trigger block and their components too."

John

Craig on making a ring block for side-catch lever BSAs

I have made a couple of these catches so far. If this helps anyone i am happy.

I use a 3mm mild steel plate cut 11 mm wide. I then use a radial arm saw set at 15 degrees and cut a 10mm groove in a 2x4 block of wood.

Insert the steel strip into the cut out and file level with wood.

Do this on both side and test fit.Barrel steel is harder than the plate and you can tap the steel plate into the dovetail on the barrel.

This will shave off the mild steel leaving a perfect fitting mounting block. the catch is obvious

Eddie/Henk on prewar BSA/LJ piston sizes 

In relation to a comment on the piston in this gun (re-tapped):

Eddie said:

"The Lincoln... is a 43" [piston] as per the later 43" IMB/IMD's that all share the same piston dia / length. They also did junior / Light / Ladies gun with this same piston dia, and a Juvenile gun that was smaller in the first 1905-1918 period.

The "long" pistons were fitted on just the 45" BSA Standards post 1919 as far as I know, I don't know if the very early (at the end of the first period Standards) 45" guns had them as well.

Basically a skirt extension to the existing sporting unit plus a longer rod....(the same 45" action in the earlier period was called the Sporting Model and was .22 only). The post 1919 Standards also had a different stroke to the Sporting 45" as per the piston rod length, photo below shows piston sizes in the standard BSA / Lincoln cylinder dia which all guns from 1905-1939 (except the Juvenile) share.

BSA piston sizes (from the top);

Light Pattern
43" Rifles (The BSA, Improved various, 19-39 43" types)
45 inch pre 1919 "Sporting Pattern"
45 inch 1919-39 "Standard / Long Tom etc." (basically a sporting with extended rear and different piston rod.

The 1919-39 also (in later incarnations with a patent stamp on the piston) had a threaded post as part of the front of the piston and heavy steel disc leather washer retaining system rather than a traditional leather washer set with a screw. These can be a pain if the gun has been dry fired / neglected as the post threads can suffer / strip.

I have found the later "long piston" 45" Standards to shoot more sweetly in .22, the CS (.177) versions in this size can be very good, but have also shot more than one that was a bit harsh.

Sorry I can't help with the exact date of change, but understood it to be a post WW1 feature, but also maybe on early 45" guns as above.

It can be hard to pin down dates, as BSA used to use up obsolete parts on newer guns, drag old actions out of storage etc. when demand was high........ so many guns are out there with the "wrong" bits on that are actually factory built, ...that is the appeal to collectors and also why non BSA fans get confused as to why you would have so many rifles that look the same to them Henk on BSA piston sizes."

Henk said:

BSA Improved Mod 'B' The diameter is 28 mm and the length of the piston is 104.7 mm. That's just the metal part of the piston length, not the centre part that sticks out.

The total length is 139.6 mm. It's not very easy to capture the length in a photo.

BSA Improved Model 'D' 1911 The piston is 129 mm long while the total length is 173 mm.

BSA 1929 Standard No. 2 (serial no. S43245) piston Here's a photo of that piston next to the shorter IMB piston.

The BSA 1929 Standard No. 2 piston itself is 155.5 mm and total length is 179 mm. The diameter is 28 mm.

Lakey/Eddie on Light Pattern power etc 

Lakey: "I think 6-7 ft/lbs is about right, but dont worry too much about stressing the guns out, as most parts were made from billet steel, so I dont think you will bend cocking levers etc. Too strong a spring can make them harsh on firing.

"For best accuracy, treat the barrel to a deep clean, as it probably hasn't been done for 80 odd years or so. Good bore cleaner, and thorough scrub out with a phosphor bronze brush will tighten up your groups a fair bit. then you should be able to shoot 1/2-1inch groups at 10 metres with the right pellets."

Eddie: "I have just been playing with a tidy example of one of these. I think 600 fps is the highest I have seen from a VGC and well run in example, most seem to go 550-575.

"The one I was testing liked old BSA pylarm (Wasp) pellets best giving 575 fps @ 5.93 FPE. Worst was RWS R10 match @ 4.71 FPE....So you will see pellet choice is important. A lot of folk (myself included) have found that Hobby pellets are the low weight these guns seem to like, and shoot well at the ranges this borderline Junior (L = Light or Ladies model) sized gun was intended for.

"Accuracy...Well you have to bear in mind the age and life experience of the thing, many have been abused for decades and have had ball bearings / nails / all sorts shot though them, a look though posts on here or on the vinatge forum will have you amazed at what has been pulled out of these, so it all depends on its history, the 'newest' of these will be 77 years old now, the oldest will be 111 years old

"If you are lucky enough to find one with a mint bore, it will match practically anything made since, the limiting factor being the fact that the trigger pull is half the weight of the gun which means most shooters raised on Rekords and CDs will 'pull' shots all over the place, for a person used to modern guns these oldies respond well to a lot of practise and experiment, they can shoot very well with a hold (supporting hand) just in front of the trigger guard too I have found, so play with that too.

"In most cases, if you rest one and gently squeeze the trigger whilst keeping aim (on a well sorted gun), you will be very suprised at the accuracy, I have a .22 which will match my HW80 out to 40 yards with open sights, and a couple of .177's which also shoot very well...

"Lakey's advice about the clean is well worth doing, as is pulling the tap and cleaning the pocket to check for anything that should not be present, at this time check the number stamped on the tap base and compare to under the barrel as they were hand lapped matched when built, so if you have a 'shotgun' this may be the cause.

"Build quality...Nothing has been made material wise to campare with these since the 1950's, full stop!...But they do have a weak spot which is the breech block / cylinder area, the trigger guard screws must be kept snug, as must the stock or else accuracy will suffer but more importantly damage will occur over time.

"P.S. IMHO and from what I have done in the past, these seem to like leather seals best, I have done a buttoned/Maccari conversion in the past and it was slammy and harsh although the FPS went up marginally. A well run in leather washer is remarkably consistent too. With many of these prewar guns I have had/still have single figures of FPS in variation over a string of shots when well settled in.

ATB, Ed"

Lakey on improving velocity after new piston seal 

In response to questions about low power, he said:

"Sorry to hear that your BSA appears to be down on power. You say that you have changed the spring and leather washer.
Did you size the new washer when you fitted it, so that it is only a good light sliding fit in the cylinder? ( ideally the piston should be able to drop to the bottom of the cylinder under its own weight, when released) Often new washers are fitted tight, so they create a lot of friction and slow the piston down, which can reduce the power. Also are the screws on the keyhole shaped tap retaining plate tight, as some leakage can occur if the screws are loose.

Finally the No.2 bore is 5.6mm, as opposed to 5.5mm of modern .22 pellets. the possibly lose fit of the smaller pellets may be adding to the recoil. Old wasp pellets in 5.6mm, give a tighter fit in the bore which would cushion the piston better, and give possibly less recoil?

I always think that it take possibly 500-1000 shots to properly "bed in" a new piston washer. That bedding in process forms the new washer to the cylinder dimensions, and creates the best seal."

In a follow-up, he added:

"I would say that the washer is still a bit tight, as a 10-15 second drop is still quite slow, and if the piston washer was sized dry, it will swell a bit with any oil that is added. I think another sizing session might pay you back with some added velocity.

The T pattern guns originally were fitted with a single mainspring, however I have found that a two piece mainspring works better, and gives a smoother firing cycle.John Knibbs, or Chambers is a good place to start here, and use (around 500 or so pellets) should have the gun running sweetly. I dont have any experience of synthetic seals in these guns, I have always replaced leather with leather. I do believe that these guns need a moist piston washer, and I add a few drops of oil every 1000 or so shots, through the loading tap, then leave the gun to stand.

The other thing you can try is a deep clean of the barrel. cleaning the bore, and polishing it, will maximise on the speed of the pellet, and also should contribute to the guns accuracy."

Jake on damaged trigger block screws 
 
Here I will be talking about my experience on removing badly damaged and seized trigger adjustment and lock screw from my BSA Club Special. First a bit of back story. This rifle was owned by my grandfather from the mid 1940's up til summer 2017. It has spent most of its time in his office gathering dust these past 30 years but before that it was a well used shooter.
 
So when I got the time I wanted to give it a good service to make sure everything is working as it should. So when I came to taking the trigger block apart I was downtrodden to find that someone (probably my grandfather) had tried to adjust the trigger in the past and forgot about the lock screw on the other side. And in the process managed to damage the adjustment screw pretty badly. And to add insult to injury the screws were all seized after many, many years of not being looked after. 
 
So i set off trying my best to get them out, now since both screws were badly damaged I knew I was going to buy replacements so ill admit that I used a less than adequate cheap screwdriver to try and get them out. But karma got me in the end and I wound up damaging the cheap screwdriver, might I add that the lock screw I was trying to get out remained untouched by my effort!
 
So at this point I was stuck but thanks to the handy engineering knowledge my father has accumulated over his long 30 odd year career, he left me with this wise and wonderful knowledge.
 
Get a flat hole punch and hit it with a hammer.......
 
Seriously, this is what he said. 
 
So with caution, I followed his advice. And to my amazement it worked!
 
Ok, so here is a brief explanation.
 
The screws I were trying to remove had badly damaged heads as show in the pictures. And the head of the screws were burred upwards and so were near impossible to get a grip. 
 
So the idea behind hitting the screw heads with a hole punch is that it flattens the heads down again (And if the screws are seized, it can help loosen them a bit). So once the heads are flattened down with the punch and hammer (remember to use caution when doing this. Make sure you have a soft area to lay the rifle onto and take your time with the hammer, should only need a few good hits and that is it, also make sure the hole punch is a near match to the head of the screw. If its too large you are going to damaged the rifle body, too small then its just going to make things worse, in the word of Goldilocks, it needs to be just right).
 
Once you have flattened down the screw heads, get a decent screwdriver and whilst apply a decent amount of pressure downwards, turn the screw and it should grip and start to turn. Once it starts to turn you have got it. 
 
The threads on mine were all fine so I went and put the old screws in a spares tin since you never know when they might come in handy. 
 
And there you have it. In the end all what was needed was a bit of courage, wisdom and a good hammer to get things sorted (shouting and swearing at it may work but this still needs to be proven)
 

 

 

 

 

 

 

 

 

 

 

 

Lakey on fitting a single spring to an Improved Mod D

See also:

https://forum.vintageairgunsgallery.com/vintage-bsa-resources/vintage-bsa-lincoln-jeffries-technical-tips-faqs-2/#post-500

He said:

"Nothing wrong with fitting a single spring.

"In my opinion, guns fitted with pairs of counter wound springs shoot a bit smoother than guns fitted with single springs, but that is just a personal observation.

"Protek are currently advertising a pair of used flat section main springs on their website for £15, or they are also offering Airsporter springs at not a lot of money, which from memory can be fitted. Both would give a nice smooth shooting cycle.

"It pays not to overspring these guns, as you can end up with very harsh recoil characteristics if you try and overdo things."

Lakey

Lakey on evolution of BSA triggers

The very earliest triggers were adjustable with a set screw , and lock nut, which went through the front of the trigger guard, and acted on the trigger itself. The idea was that you slackened off the lock nut and adjusted the trigger. Finally to re-tightened the lock nut to prevent unwanted movement. This system was in place until 1913, when a similar screw was employed on a re-designed trigger with a double safety sear employed.

The airgun range was simplified 1919, with the arrival of the post WW1 BSA Standard air rifle. The first of these used up some pre-war parts , then moved to the two hole trigger block, with the none adjustable trigger, which was set at the factory ( the exact weight of trigger pull was marked on each individual rifle). These triggers were good, but match shooters demanded more refinement, and finer trigger adjustment.

BSA designers had a re-think, and came up with a new trigger system, which featured a clever internal weight adjustment. Externally the main visible difference was the three hole trigger block, with a small trigger adjustment screw and lock screw set behind the trigger, and sear pivot screws. This new trigger was introduced in 1922, and lasted right up to 1933, when the air rifle line up was changed again, and changes were brought in ( presumably for cost cutting reasons)

This new 1933 range of rifles did away with the tree hole trigger block, and internal trigger adjustment, and went back to the pre-war design of the set screw through the front of the trigger block. This arrangement stood until production ceased because of WW2.

Lakey

BSA/Lincoln Jeffries visual indentification assistant 

See HERE.

Lakey on underlever releasing when rifle is fired 

it is more than likely where previous owners have slammed the underlever back on the catch post without pushing the button. Over time the end of the underlever catch post gets bent over where the notch is. Then the wedge on the button catch itself can no longer get a full bite of the post. The recoil of the rifle going off unclips the cocking lever.

there are a couple of remedies that I have tried.

You can replace the catch post that dovetails on the underside of the barrel

You can identify the distortion in the post and re-open the notch a bit with a needle file, until the wedge behind the button gets more of a bite on the post.

You could also apply heat to the post, and bend it back into shape (BUT I HAVEN'T TRIED THAT MYSELF) , and if you did, it would be wise to remove the post from the barrel

If your gun does suffer from the above problem, you can usually see that the button comes fully out on the unclipped cocking lever, but only comes out half way ( or worse) when the cocking lever is clipped back onto the gun.

Guy on stripping a BSA Breakdown 

BSA Pre War Break Barrel Strip.

As the pics have gone from this and I have now bought one of these guns, I thought I would add a little to this post.
Unscrew the 2 trigger guard screws and remove the trigger guard. Unscrew the barrel pivot screw and lift the cocking arm out of the slot in the cylinder to free the barrel and breech block. You can unscrew and lube the cocking arm pivot screw now if you want. There is a little pin in the breech block, that retains the barrel plunger. You can drift this out and remove/clean and lube the barrel plunger and spring. Sometimes a little block of wood helps for pushing plungers back in far enough to relocate the pin.
Unscrew the trigger block, keeping tension to stop it flying as it clears the cylinder. The mainspring and piston should now come out. The mainspring on mine had a rough end so I heated it and flatted it. I think the piston washer should be a normal leather cup washer set up with a buffer and the dimpled steel washer, held by a screw. Unfortunately, the buffer washer was missing on mine and 5 small steel washers had been used instead. This meant that the piston had been slamming into the end of the cylinder and also damaged the head of the screw that holds the washer on. The piston rod should unscrew once you have undone the little lock screw, but as mine looked fine I just cleaned the piston up. I made up a buffer washer and found a dimpled steel washer to complete the piston washer set up. Before I put the gun back together, I undid the trigger pivot screw and removed the trigger and trigger spring for cleaning and lubing. I also cleaned out the trigger housing. I find this is worth doing on the old stuff as you might have grease that could be somewhere between 70 and 100 years old!. The trigger spring is located in a hole in the trigger housing and the trigger slid back in and lined up and the pivot screw replaced.
Refit your piston and mainspring and screw the trigger block back on. When It is located, replace the trigger guard and the 2 screws. Before you replace the barrel, it is worth checking the breech seal washer as these are often old/worn and are often the cause of low power.
Locate the cocking arm in the cylinder and locate the breech block in and barrel in the breech jaws. replace the pivot pin.

This was very low in power and I suspected the breech seal, which I had left in for now just to see how much difference it would make. Once the new seal was made up and put in, the gun shot quite well. I would say it is quite a well made little plinker.

Eddie on failure to cock/elongated piston slot 

Question:

I've got a very old Lincoln Jeffries (suppose they all are now) light pattern that will not cock. I've gone through all the likely scenarios & discovered that it looks like it's being caused by wear on the face of the rear piston slot. A very helpful sketch of one is on the web that shows that particular one as being 0.366 inches from the face of the slot to the rear face of the piston. The one on mine measures 0.322 as far as I can make out, anyway it's less than 0.366 & even with varriations in production I reckon it's on the small side. Just to confirm things I've put a cardboard spacer in the slot & tried cocking the rifle. The "built up face" allows the rifle to cock normally & looking at the button on the cocking link.....it looks ok to me no obvious wear.

So what to do..... build up the pillar under the cocking lever button ( even though it doesn't appear to need it (dont like that idea much) or take a big gulp & try to build up the piston slot?
Or do I try to find a piston for it.? I've only got acess to a stick welder & am well out of practice for thin stuff, maybe it's time to get in the groove again.

It's annoying as I've just made a face plate for a bell target out of 3/8" plate for it to go up agsinst & test both it & me; well thats on hold for a bit.
Given the situation what would your advice be please?

Eddie agreed with Pete who suggested 

[getting] the original piston built up with tig or mig weld to replace the worn metal.

Eddie added:

Clear photos would be handy, also of the bearing area to the rear of the cocking arm, these are cast steel on the Beezas and normally don't move like the Webley MK3 ones do (the Webleys are known for it, to see some folk cocking underlevers is painfull as they yank the arms down, then as the secondary arm bends, just yank harder till it's bent too far and won't latch.....I have done several Webleys in a flypress with nylon blocks, they do straighten back).

The BSA Piston is cast steel as well as the cocking arm, again use A15 filler and file to suit on the piston I would say.

Brazing with Nickel Bronze rod will work too, just remove the piston rod to keep the heat off it, as these are hardened.

Louis' replacement leaf spring for Improved mod 'D' rearsight 

Crafted from steel from a tape measure.

Louis said:

This morning, I finally started making a spring for the rear sight.
With the great tip to use a tape measure.
I have cut out the rough shape (easily done with a cheap pair of scissors, and a Stanley knife) and will finetune with file/Dremel.
It's now in vinegar to make it easier to remove the paint. Then I will try cold blueing.

Thanks to VAGF. I put this photo on my phone and zoomed out until the width of the spring was the same as the width of the rear sight. Then I put a piece of paper on the photo on my phone, with the screen as bright as possible, and drew the contours of the spring on the paper.The tape measure metal is too thin and does not have enough spring power otherwise.
But with two layers, it works well (although it won't win any beauty contests!).

Lakey on cleaning/lubricating BSA underlevers upon purchase 

See also:

https://forum.vintageairgunsgallery.com/vintage-bsa-resources/vintage-bsa-lincoln-jeffries-technical-tips-faqs-2/#post-494

He says:

It is wise to give the barrels of these old underlevers a DEEP CLEAN when you get the chance as it is probably the first time it has been done in 100 years. Also it is also worth dismantling the simple trigger mech and clean and relube all the components. Again, this could be the first time it has been properly done. Dust and grot always builds up in these guns, and it is always worth the trouble to clean all parts. Especially if maximum accuracy is required...

To clean my barrel, I would first use a cleaning rod and loop or similar, and put down a patch of lint free cloth, to remove any loose debris that might be there. Then I would use a Phosphor bronze brush and bore cleaner, to scrub out the bore (I use Parker Hale 009 but others are available) . The idea being that you want to try and remove any and all lead fouling that might be present in the rifling. Once I had done around 10 passes up and down the barrel with the brush and bore cleaner, I would then use another cloth patch and swab the bore out. Repeat the above until the cotton patches come out clean. Finally I would put a few drops of oil on the final patch and pass it up the barrel a couple of time to leave a thin film of oil up the bore. If you can clean the bore, then accuracy usually does improve and group sizes do improve...

The reason I make emphasis on the words "Deep Clean" is that some people consider a couple of felt pellets fired down the barrel a "Barrel Clean". When you are dealing with 100 year old guns that may not have had a clean for many years, you need to be a bit more purposeful in your approach. It stands to reason, that the closer you can get your rifling to completely clean - as it left the factory, the more accurate the gun will be. Lead fouling is a very gradual thing, and a little will not make too much difference, but over 100 years I believe it can affect accuracy more that is generally supposed.

John M adds:

If an old BSA does not group as tightly as it should, a barrel clean is often all that is required, particularly if the rifle is in otherwise good condition and all screws, sights, etc are tight. I've cleaned many a barrel to discover the initial patch coming out jet black and once cleaned, those groups tighten up, which is very satisfying...

I simply use a rod with a synthetic covering and brass loop holding 4x2 cut down to size, depending on whether it's a .177 or .22. Rod it through until the patches come out clean.

Eddie/Lakey on tap alignment 

The tap on Louis' Light Pattern did not align with the bore.

A clean of the barrel and breach led to some improvement.

Eddie said:

Seeing that last photo, I would like to see a photo from above of the tap inserted to gauge how deep it is going in, if a gap then maybe look for a burr at the smallest end of the taper, or a high spot (use a permanent marker / lay out fluid on the degreased tap, insert and twist, and see what the bearing area is.).

Also clean out the socket and then put a small ball of plasticine / putty on the tap small end and push in hard to see if clearance and not bottoming, although it looks fine, the small end does look marked / burred at 4-6 o'clock in your photo.

Apart from the above, if the tap is hard on the breech forging, I would scrape the surface and deburr the hole edge...

Cleaning the breech area will have no effect on the tap fit, this is down to the taper.

The slightest bump or burr will have the effect of stopping the tap dropping right in, the blue / marker test being the first thing to try, this will show up any damage at once.

'lamin8', who seems to know exactly what he's taking about, added:

I think I'd pop a solvent soaked piece of cloth into the breach plug hole, & similarly soak any other faces that might harbour crud etc with paraffin or diesel or dismantling fluid, not WD40 (seems to dry out & "skin") & leave it to soak for a couple of days or more to try & soften up what ever is in there. Don't think I'd use steel wire brushes, phosphor bronze probably. The steel might well be pretty hard but I'd try to keep anything likely to be as hard or harder than any component parts away from it unless there was no other solution. Even wooden scrapers might work ok. You could think about brass or aluminium. Scrapers made from bits of scrap if you have any to hand. Files......make me nervous, but I'm a wimp.

I might sound over-cautious but lack of experience, practice & over enthusiasm has made me stop & think things through a bit more than perhaps I should have done in the past. Not actually completely messed something up but I came pretty close.

Lakey added:

It seems to me that the tapered tap is not seated quite deep enough in the hole, to precisely line up with its loading hole.

People have already suggested clearing out the hole that the tap plug sits in, but if you look at it from the other direction, it could be due to insufficient pressure from the keyhole shape tap cover end. The lever end of the tap contains a a plunger and spring designed to help index the tap in the open and shut positions. This will exert a pressure on the tap pushing it towards the blind end of its reamed hole. If there is (1) a build up of crud in the top hole at the blind end or (2) insufficient spring pressure off the keyhole shape tap plate, it could result in the tap plug being slightly proud in the hole, leading to the missalignment problem. This could be due to a missing/broken plunger spring, or the tap cover screws being loose of damaged.

Eddie added:

The bit your thumb pushes should be practically zero gap or at least miniscule in the 1000's of an inch range, or even just touching the rest of the gun, as per this very original and little used example of a Light Pattern I got a while ago.

You can see the movement tap casting on this gun has just barely removed some of the blue on the gun itself at the place where it goes in (the breech forging area) as it has been opened and closed over the years, so actually just lightly touches the gun itself on this gun... [in another rifle] I have had a 0.002" feeler gauge just possible to fit the gap, but nothing ever like on your photo.

After a little careful filing, Louis' tap was centred and power improved.

Eddie pics/dimensions for c.1908 cocking lever latch post 

Eddie and Lakey on breech tap closing plunger and spring  

The plunger is the key to a positive closure, and the spring needs to be quite stiff... ball bearings sitting on springs etc. simply don't give the same positive effect as a plunger.

He posted a short video illustrating what a BSA tap should look and sound like.

He added:

Spring O.D. is 0.174 inch.

The location of the tap plate can affect the plunger position and therefore how positively the tap opens and closes. For example, Louis' tap was not closing with a firm click when down. Lakey pointed out that the plate was wrongly located in relation to the plunger. He said:

Your keyhole shaped tap plate isnt quite straight, as you have the wrong sized screws holding the plate in position. They should match in size and shape, and also precisely fit the countersunk holes in the plate. If you look, the right hand screw isnt central in the countersunk hole. That will have an affect on the lock up position of the spring loaded plunger. If those screws have been like that for years, you may have got some wear on the indented hole on the inside of the tap plate...

Louis' keyhole tap plate:

Eddie on re-lubricating a post-WW1 BSA trigger 

He says:

A pair of tapered screws were added on some guns so you could "adjust" the trigger. Basically they lessened the sear bite / overlap in the same way as pulling a bit on the trigger.

A blade and a rocking sear, small spring and plunger, all come out together with a wiggle if both trigger pivot screws are removed. To replace reverse the process but you may need a pointy thing (I use an engineer's scriber with the end dulled) to align the hole in the sear to get the second pivot bolt in.

Just degrease, check all the sear and blade edges, you can (lightly) polish the plunger end if fussy, and also the pivot screws where the trgger and sear bear, and use a high pressure or moly lube on these pivots and a dab of moly grease on the plunger end.

Scoping a prewar BSA air rifle 

See also:

https://forum.vintageairgunsgallery.com/vintage-bsa-airguns-talk/printed-telescopic-sight-mount-for-prewar-bsas/#post-8813

Baz points out:

No need to weld these days, there are really effective glues can can easily be dissolved with no damage. I use Tiger Seal to put scope ramps on.
Nice to shoot very tight groups with failing eyesight.

With thanks to Trev M.

This mount was designed by Jeff Jongmans. For details of a 3D printed reproduction by David of dm3d-designs, see this link:

With thanks to Ken for these pics of Jeff holding Trev's rifle:

With thanks to Eddie:

Eddie on removal/reassembly of a 1930 BSA Standard trgger 

With thanks to Ed. He says:

Quite simple, two parts ie. trigger and rocking sear and there is a spring and rounded top hat between these parts.

Undo both pivot screws and remove / replace the group as a pair, the spring tension on refitting will stop you getting both the pivot bolts back in, do the trigger first, then look and you will see the sear maybe half a hole out, I normally use a scriber or tapered pin as a "podger" to ease the sear over from one side, whilst maintaining thumb pressure on the screw the other side till it starts in, pivot screws have tapers on end to aid re-assembly...

If all good, bit of moly in the spring pockets and the pivot holes (check pivot pins as well for burrs etc. and polish if you want to).

The trigger weight adjustment system is basic, the screw to the left of the gun "ADJ" is tapered with a flat end, the "lock" screw opposite butts against this to prevent movement.

If you back out the "lock" screw, and screw in the "ADJ" and closely observe the trigger, you will see it move, basically the tapered part of the screw bears against the rear upper surface above the fulcrum of the trigger and effectively is pulling it back (as the taper diameter increases with the screw going farther into the block).

If you are keen invest in a low range spring balance (Fishing type) and you can set the trigger at 3 pounds if all edges are in good order, would not go lighter than than personally, too light can cause damage if the gun is knocked or whatever and it goes off, as the sear faces are glass hard and can break.

Once weight is set, you need two screwdrivers, one to hold the "ADJ" screw, and then screw in the "lock" till it butts against the "ADJ" and nip up securely, re-check after locking, some guns have stiffer screws that don't move, but normally the lock screw will move the adjustment screw a tad unless the adjustment screw is held.

The gun will work and is safe without the adjustment screws fitted, so pop them out (taking note of turns to remove the ADJ one, and you will see how they work, always easier to observe the item than waffle on about it!