The designer of this SSP (single-stroke pneumatic), Graham Trim, wrote:
Back in 2006 I was talking to a friend about air weapons, he was very much interested all things shooting related and was very interested in us doing something together as he also had substantial business interest in the Middle East. We decided that the apparent holy grail of the Airguns's industry then, was the Single Stroke Pneumatic Rifle, something that could compete with a PCP without the requirement for any separate recharging gear. It was decided that I would develop it and he would assist with funds to keep me going whilst I did it.
I had, had some thoughts on the matter from several years back and was confident that it could be done. However, I should mention at this point that several companies had tried to do this previously and had either gone bankrupt or very nearly lost the companies in the process. I also understand that Daystate sunk quite a substantial amount of funds into trying to produce a production version of such a weapon too.
There were some designs produced with varying degrees of success:- John Bowkett produced a number of Single stroke Pneumatics I have seen a few JB 1s and I am sure there were others but I think they may have gone under the Titan name. In the mid 1980s Richard Spencer designed and produced the Air Logic Genesis; this was in my opinion one of the very best and I think around 175 were made. In the 1990s Parker Hale ventured into the Air gun market with the Graham Bluck designed Dragon rifle and I gather around 2000 of these were made but reliability became the main problem with that one.
In all the above cases the cocking load was very high and considered to be a real problem by many potential customers. So much so that no one else bothered to try again for several years because everyone would disregard it as too hard to cock. Whilst I had had an idea back in the mid nineties of how to do it, I decided to wait until it felt like the time was right and hopefully this was it.
And now for the first of the technical bits! I know from the work that I did with Brocock back in the air cartridge days that in order to produce 12 ft lbs of energy at the end of a 400 mm long .22 barrel it requires 120cc of air compressed into a 0.6cc space I.E.200 bar pressure. This assumes that there are no losses due to heat and that the air is released directly behind the pellet. However, in most cases the barrel is situated above the power tube and this means that the air is released from below and that is not a very good transfer port path for efficient propulsion of the pellet. This tends to mean that more than 120ccs of air is required to be compressed. Furthermore, in order to compress the air to 200 bar a piston load of 1061.85 kg is required assuming a piston of 26 mm diameter and a gap between the piston head and valve face of around 1.2 mm. The cocking force comes from the need to overcome a load of more than one ton and that is a fact that cannot be changed, or can it?
Over the next 12 months I tried various different designs of pump system to try to produce a full power single stroke rifle without having too heavy a cocking load and whilst it is easy to produce a rifle of around 6 ft lbs of power getting anything over 10 is not as easy. It can be done but the cocking load is significantly higher. I started out using the Crows foot type of leaver as it was used extensively for cocking crossbows in the Middle Ages and is a very efficient type of leaver. However one of the real problems with producing a full power single stroke rifle is that it requires a very long stroke to compress the necessary volume of air. If we ignore the effect of heat and friction etc. Initially there is very little pressure required as you have to go half-way to increase the pressure to 2 bar then each time you half the distance between the pump head and the valve unit the pressure doubles. This means that the pressure really shoots up in the last few millimeters and the accuracy of the final volume is paramount to performance, 0.1mm of the stroke can make a real difference.
Now Let me run a couple of basic ideas by you; 1 if you blow up a paper bag and close the top with your hand, when you release it, it will drop to the floor. However, if you blow up a balloon when you release it, it will fly around the room until empty. This started me thinking, that if I could have a container that would hold the air at pressure so that when the trigger was fired it would force the air out as it contracted, we could then perhaps use air at a lower pressure and this would be considerably easier to compress in the first place. But what pressure should we use?
Well that brings me to idea 2 if we consider a normal PCP rifle and as the pressure in it decreases the hammer system usually opens the valve further which causes the power level to increase until the air pressure in the container is too low to give sufficient velocity to the pellet at which point the power starts to drop off. From experience, I find that rifles will perform quite well down to about 70 bar pressure before too much velocity is lost. I therefore decided to use 70 bar for my pressure setting and this has the advantage of dropping the necessary cocking load on the 26 mm diameter piston to 371.65 kg a mere 35% of what is required to produce the original 200 bar pressure that everyone else has to use. This is why my rifles are much easier to cock. Furthermore, at this very low cocking pressure, I am able to put needle roller bearings in the pivot points which also helps with cocking but this cannot be done on much heavier loads as the bearings crush.
When I started I produced a rough action to prove that my calculations of volume were right, they were but the cocking load was horrific as expected. I then set about trying alternative ways of achieving the same results without the huge cocking load. This involved designing and making a series of test bed units until finally I found the right one. This took me 3 years of sweat and toil as I was determined to produce a minimum of 17 ft/lbs of energy in .22 in order to give myself any hope of producing a .177 rifle capable of anything near 12 ft/lbs. However, that is another story and I will address that one at some other time.
At the end of the first 12 months I had produced this rifle but whist it performed well giving around 9 ft/lbs in .22 and 6 in .177 with a fairly easy cocking stroke it became obvious that it would never be capable of giving the performance I was eventually looking for. However, at this point my backer decided that it was going to be a long job and dropped out, so from here on in, I was on my own...
By Now we were into spring of 2007 and I had made the decision not to continue with the crows foot style of cocking leaver as it was not rigid enough to hold the pressures of a full power rifle when cocked. I now reverted to a more conventional type of leaver and started experimenting with various ratios of pivot point to operating angles until I found something that was not too cumbersome and felt right when in use. Another bonus of this type of leaver is that it could be concealed, in the underside of the stock.
I now began experimenting with putting the Disc Springs in the piston rod so that the head contracted under pressure during the cocking stroke and extended within the firing cycle, thus accelerating the air along the barrel behind the pellet. This involved the use of far heavier springs than had been used previously on the crows foot version since the load area was now the full diameter of the tube IE 26mm. I never cease to be amazed by the length of time it takes to find the simplest way of doing something!
I stayed with the rotary breach as it is the simplest and safest to use then started to produce a range of actions to test various valve systems both "out of balance" and "blow off" types. Whilst the out of balance valves, gave a nice feeling trigger action, they had to be kept very short to avoid the loss of propulsion volume. The blow off valves had a habit of sapping energy if the poppet was too heavy and producing recoil which whilst very small did somewhat defeat the object of producing a totally recoilless rifle.
This stage of the development program took very much longer than ever expected because every action worked well but only produced around 6 to 7 ft/lbs of energy at the muzzle. I knew that it had nothing to do with rigidity of the cocking leaver as it was now in compression unlike the previous one that had been in tension. I must admit to beginning to doubt if the 70 bar pressure was enough to do the job but stuck with it for a little longer. Plus in between development I was having to repair air rifles for local shops and make component parts for a local food producing company and even one man who was building his own private aircraft in order to keep myself and pay all the expenses.
After prolonged testing I realized that the problem was timing IE there was a time lag between the valve opening and the compression of the disc springs having the desired effect. It was vitally important to get the valve open completely as fast as possible for best results and as it turned out, a tight barrel was required, so that the pellet did not begin to move too quickly because if it did then the acceleration effect did not happen. Perhaps I should explain that the acceleration effect is caused by the ratio of the cross section area of the piston over the cross-sectional area of the barrel times the speed of the disc springs. So for a 26 mm diameter piston and a .22 barrel this ratio is in round figures 22 to 1. IE the air speed in the barrel is 22 times faster than the rate at which the piston is moving.
Trying to ascertain what is happening during a firing cycle is very difficult especially when the lock-time is so short. However, with plenty of practice I began to get a feel for it and was able to redesign and change the relevant parts to get the performance that I was looking for.
This Development Rifle was always known as the Merlin because eventually when using 21.4 grain pellets I managed to get 19 ft/lbs of energy out of this one in .22 calibre.
This is the rifle that was shown to Webley back in 2008 but they decided that, whilst they wanted a single stroke rifle, they wanted one with a Bolt Action which necessitated a completely new design being under taken as a bolt system is nowhere near as efficient as the rotary breach on this one. This actual rifle was purchased by a collector back in 2009 and it was marked up with the name and serial number at that time. It has changed hands a few times since then. Recently it has been offered up for sale in the Holts Auction on the 20th of September 2018. However, we last saw this rifle approximately 12 months ago and noted that it had been unfortunately modified and doubt if it will now perform as originally intended. Our offer to return it to original condition was declined by the then owner.
Early the following year I clearly remember driving up to the Webley HQ for a meeting with the directors Mike Hurney and Roger Williams to discuss the possibility of them purchasing the design of my new Single Stroke Pneumatic Rifle I do not remember the date but I do know it snowed both ways. The meeting had been set up by a mutual friend of mine and theirs.
After a fairly short meeting an agreement was reached but unfortunately they did not like my rotary breach and wanted a Single Stroke rifle with bolt action and ideally a swan necked bolt handle. This unfortunately unappreciated by them at the time necessitated a complete redesign because a bolt system is no where near as efficient at driving the pellet as the rotary breach which deposited its air precisely in the centre as required. This meant that a different valve would have to be developed and as it turned out a completely new trigger system to go with it. This in turn required a completely different stock design. There had been no up front payment but a fairly generous royalty package was agreed so I was back to having to do more development with no real income in the short term.
At the time I was working from a unit in Downton on land that the Landlord wanted to redevelop and therefore I needed to vacate. I was lucky enough to meet Bradley Howard and his partner Michael Dove who between them ran a very good small Engineering business called Mikina and they were very much interested in producing the new rifle for Webley. It was agreed that I would have a mezzanine floor area in one of their their workshops to work from while I produced the prototype new rifle and that we would talk further when it was finished and ready to go into production.
Moving my workshop and the redevelopment of the new prototype rifle took a further 5 to 6 months and it had become apparent to me that this rifle could only be produced in .22 calibre initially and that further work would have to be done to make a .177 version at a later date. However, Webley approved the prototype and agreed manufacturing terms with Mikina for production to begin. It was during the test demonstration up at Webley that Mike Hurney came up with the new name " Paradigm". Meanwhile Mikina went out and purchased a Mazac integrex 200 1v multi axis machining centre to produce some of the more complex components faster than would otherwise have been possible on their already extensive range of 2, 3 and 4 axis CNC machines.
This is a picture of the Finished Trigger assembly and a selection of some Paradigm parts produced on the above machine. If you watched the video of the machine did you notice that it did the de-burring too? How many times have we all had rifles with the sharp edges still on them?
However, Having one of the most up to date pieces of equipment in the country, may have been a shot in the foot for me because at that time we were at war with the Middle East and an extraordinary amount of ordinance was being used which had to be replaced and this machine ended up being commandeered to make some critical parts required. This effectively pushed the Paradigm project back by around a year.
This is a 3D model picture of the eventual paradigm action shown in its cocked position and if you look closely you will notice that the air is trapped between the piston head seal (which has retracted by compressing the disc springs) and the valve face. It will be released by the poppet seal situated in the valve body moving back to open the transfer port when the trigger is operated.
In addition to all the cocking forces and timing issues that have to be solved in order to make a reliable and efficient Single Stroke Pneumatic rifle, by far the most important consideration is the quality and design of the seals involved. I consider myself very lucky to have an excellent working relationship with Adam Hooper operations director of Martins Rubber in Southampton. It was the combination of us getting our heads together to produce all the specialist seals required that made this project work.
In most cases I design a seal that I require, their technical department will then cast an eye over it and if viable they make me some samples which I then test and together we develop what is required for the function it has to fulfil. I think I am right in saying that the eventual poppet design was Adams Idea. Not only is that an unusual design but the material that it is made from is actually especially made for it too. We tested one of the rifles by cocking it on Friday afternoon and then I fired it on Monday morning with very little loss of performance.
The Paradigm was ready to come to market at the same time that Webley decided to drop their own sales staff and use Highland Outdoors as their sales outlet this effectively closed their operation in fact as far as I know there is only one very valued member of technical staff left and He has been there for ever.
When this happened Highland Outdoors dropped the Paradigm from their books I suspect because since it was to be made in the UK the ratio of purchase cost to sales price was not as good as they could get from Turkey. At this time Mikina had just made delivery of the first preproduction rifles to Webley but having allowed them to keep one, we withdrew the others back to the factory. Therefore, the Paradigm is a very rare rife at the moment because there are only the four that I have supplied at various times and I am not sure if it is three or four left back at the factory.
I tend to feel that there is a time and a place for any particular type of product and I think the big requirement for a Single Stroke Pneumatic Rifle, if indeed there ever was one, has come and gone, now that there are cheap multi shot PCPs and pumps available from around £300. However, there are always a discerning number of people who want something unusual especially if it is made to a high quality standard.
When Webley closed the project they signed over the Patent, the Paradigm name and the 150 or so stocks that had been made by Custom Stock to me. However none of it, is of any use, unless I have the actions to put in them, otherwise they are just a lot of expensive fire wood. This left Mikina, Martins Rubber and me vastly out-of-pocket and it took all of us a very long time to get over it. However, Mikina have now agreed that if I can get enough customers, they will make the actions required but the minimum batch size would be 50 rifles. My objective would be to try to sell 150 to use up the stocks I have now got.
I have decided to do this via our Patreon membership and anyone wishing to obtain one must first join us on that site which will cost $1 per month when they will find further details about the deal. Alternatively you could email me and register your interest,
*10/10/2018 News Flash. *
The First New Paradigm to be built in many years is nearing completion and will be ready on the 13th of October this year. Anyone wanting one in this instance, should make contact via the Contacts page to register their interest as we cannot sell from here.