Hy-Score strip down  


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6th November 2019 18:03  

Hy-Score strip down

These observations by LeonardJ when he stripped a Hy-Score:

"One of the more unusual features, for any spring gun, is the presence of a lubricating wick on the piston head. The next thing that becomes apparent, in spite of being a concentric piston action (barrel runs throught the center of the piston), there is no seal present between the ID of the piston, and the barrel - just a very smooth, close tolerance hole through which the barrel passes - the lubricants form the seal. The piston head is fastened to the skirt of the piston in a manner that allows the head to "float" - no doubt to help maintain a seal. The spring guide also "floats" within the confines of the mainspring ID. The gun uses a common O-ring seal on the piston head, and a proprietary seal within the rear end cap, which seals the main compression tube, so that all the compressed air is directed to the breech, and thus to the pellet."

Thanks to Len for these pics:



With thanks to Mike Van Winkle for posting this on the American Vintage Airguns forum:

Hy-Score Model 803 Pistol Disassembly Instructions

NOTE: Although the following instructions are intended to be used for disassembling a HyScore Model 803 Sportster, given the similarities between most Hy-Score models, many of
the points may be of help when disassembling a Model 800. The primary difference would
be the fixed barrel in the Model 800. For the repeater Models 802 and 804, simply remove
the repeating mechanisms first. These mechanisms are equivalent to the rear cap
mentioned below.

ACKNOWLEDGMENTS: As I ventured bravely into the murky world of spring air pistol tinkering, I found many people more than willing to
help clear up the fog. With many thanks to:
Leonard Joe for his photo (February 6, 2008 post on the AVA forum) of a disassembled Hy-Score Model 803 Sportster, excellent advice, and
Larry Hannusch for his replacement parts and encouragement.
John Groenewold for his replacement parts.
Eddie Williams for giving me Larry Hannusch and Leonard Joes names.
Don Raitzer for proving that the gun gods do, indeed, smile on you now and then.
Jeffrey Long, devoted air pistol collector and helpful pen pal.
Dr. Robert Beeman for advising me that Steve Laszlo and Andrew Lawrence of the Hy-Score Arms Corporation never did make up a shop
manual for these guns, so no original written instructions exist.
1) Unscrew the removable barrel from the pistol.

2) Remove the rear cap lock (cir clip) (#830). This cir clip sits
behind a shallow ridge on the inside of the rear cap (#810). Using a
pick (I used one side of a needle-nose tweezers), first work either end of the cir clip to begin to release it from behind the shallow ridge.
When you get it just right, one side of the cir clip will pop out. Then work the rest of the cir clip out slowly. Leave the cir clip on the barrel
and chamber casing assembly for the time being.

3) Unscrew the rear cap. It should come off easily.

4) Remove the rear cap spring (also loading shutter spring) (#852)
and the loading shutter (also cover plate) (#895) from rear cap.
First, however, note the shape of this shutter spring and how the
loading shutter sits inside with its squared-off point in the open part of the shutter spring. Also note the raised and rounded pin of the
loading shutter, and the corresponding indentation in the cylinder cover (#809) (see below) where this pin fits.

5) Unscrew the cylinder cover using a correctly sized or fabricated
spanner tool/wrench. This will likely take considerable effort and
leverage to accomplish because the cylinder cover is screwed very
tightly onto the tube. Additionally, the manufacturer put the
equivalent of todays Loctite deep inside the threads of the cylinder cover to help seal it. The reddish color of this substance will be evident
when you unscrew the cover.
To unscrew the cylinder cover, I first tried an adjustable pin spanner
wrench from McMaster.com #5735A11 that had pins with a 2.9mm diameter, the equivalent of .11417". The pins were a little small for the
holes, but adequate. However, the cylinder cover would not budge.
I eventually used two reinforced hex-head bolts that fit very snugly
into the cylinder cover holes, together with an adjustable wrench
clamped around the two bolts. The increased leverage I was able to
achieve allowed me to slowly open the cylinder cover. During this
procedure, the pistol was securely held in a padded vise.
CAUTION! This cylinder cover is under preload and compresses the main spring and piston. Open with care.

6) Remove the cir clip from the barrel chamber assembly.

7) Unscrew the main pivot screw (#836) and main pivot nut (#837) using a correctly sized spanner bit that will not damage the slotted nut. I
used a Best Way Tool screwdriver blade #8 Tamper-Proof Spanner, 1/4" Hex, STK. #86822. It could have been filed a little to thin out the
points but worked fine as purchased.

8) Unhook the cocking lever assembly (#892) and the catch (#727) from the chamber casing/tube assembly. It may help to hold back the
sear (#720) in order to allow the catch to more easily clear the casing.

9) Remove the piston (#891), mainspring (#851), spring sleeve (#831), and washer-type part (#unknown) that appears to act as a mainspring
stabilizer and sits rounded-head-up against the barrel block (see below). If the piston feels stuck or tight, trip the sear and this may help
free up the piston from the tube. If desired, remove the barrel block with front sight from the chamber casing/tube.

10) If desired, remove the sear pin (#743) and sear spring (#754) with a punch.

11) Inspect the piston and, if desired, remove and replace the O ring at the front of the piston. I used a dentists pick to lift off the old ring
easily. I replaced it with a common O ring sized 13/16" x 5/8" x 3/32" that fit perfectly. A unique oiling wick made of a felt-like fabric also
encircles the piston behind the O ring. I chose to leave it as original.

12) You now have the lower portion of the pistol to work on. To remove the grips, first unscrew the trigger guard screw (#746 but also
labeled as #745 in one of my parts diagrams). Work the trigger guard out of its slot in the bottom of the grips by gently pulling it down and
out, taking care not to stress or bend the guard. It may feel tight at first.

13) Unscrew the large vertical handle screw (#747) inside the grips,
taking great care not to lose the small frame cushion (#833) which
(apparently) can be either a rectangular rubber washer or a thin metal serrated spacer that fits under the screw head. Without this piece,
the handle may wiggle and feel loose when reattached.

14) Attempt to remove the grips by pulling them down and off the frame.

15) If you have a pistol with the original grips, you will likely be
unable to remove the grips completely off the frame. This is because the trigger pin (#741) on original pistols extends beyond the metal
frame of the pistol into small oval or circular-shaped cavities that are recessed into both sides of the interior of the grips. These cavities
hold and support the trigger pin, thereby helping to keep the grips from moving during the cocking stroke, which puts great tension on this
forward portion of the grips.

16) Grips on some pistols may slide easily right off the frame.
These grips will likely not have the small cavities for the extended trigger pin, and the trigger pin itself will therefore be flush to the
frame, and to the interior surfaces of the grips.
NOTE: Leonard Joe speculates that grips with no interior cavities may be replacement grips issued by the company to simplify repair
procedures. It is also possible that repaired pistols could be those pistols described on various forums as having loose grips (despite
tightening the main handle screw) because the grips are no longer supported by the extended trigger pins within the grips.
HINT: To correct this looseness in pistols with grips that lack
indentations and extended trigger pins in the frames, try to shim the interior of the grip halves where the frame meets the grip. I once
used slivers of two-sided foam core tape as a temporary fix. Or, replace the shortened trigger pin with an original (or made up) extended
version and attempt to fit replacement grips with indentations over the extended trigger pin (see below).
NOTE: I have examined 4 Hy-Score grips and each was slightly different in construction. Differences include no cavities for the extended
trigger pin; reinforcing screw through the exterior top rear of the grips; sloping section in the top rear of the interior of the grips;
overhanging section in the top rear of the interior of the grips which completely encompasses and supports the back of the metal frame.
One might conclude that over the long production run of Hy-Score pistols, the designers keep tinkering with the grips to strengthen them,
since they are such an integral part of the pistol.

17) You are now faced with a challenging part of the disassembly:
Removing original Hy-Score grips from the frame. Prying apart the grip ends is difficult because the plastic is very strong and thick, and, as
mentioned above, the trigger pivot pin extends deeply into the grips. Plus, you risk marring both the frame and the grips with whatever
prying tool you are using. You must carefully and slowly pry apart the grip ends at the top front of the grips so they will clear the trigger
pivot pin inside. Unless its absolutely necessary to remove the grips, or you have a replacement pair of grips available in case of disaster,
stop here and reconsider!
The grips may have been glued together on the production line during the actual manufacturing of the pistol. Or, perhaps more likely, a
special tool was used on the production line to spread apart the pre-glued grip halves and set the grips on the frame (see tool suggestion
After much experimentation and anguish, I successfully used a special pair of retaining ring pliers from Channel Lock (927/8"/203.20mm)
that have a switch tab enabling you to either grasp or spread rings apart. These pliers let you spread apart the two halves of the grip
simultaneously and slowly until they clear the trigger pin. This tool works exceptionally well at the task. It helps to have the forward part
of the frame in a vise while attempting to remove/replace the grips so you can fully concentrate on the pressure you are applying.

18) When you remove the grips, you now have the vertical striker spring (#753) (but also labeled as #743 in one of my diagrams) that is
sitting in a cavity in the grips. Before removing this spring from the grips, note where it engages the lower tip of the striker (#721).

19) The primary parts remaining are the assembled frame (#818) with trigger (#822), trigger spring (#857), striker (#721), cocking lever
assembly (#892), release button (lock button) assembly (#728), right and left locks (#724 and #725), lock springs (#756), stop roller (#732),
and roller pin (#742).

20) To remove these parts, first use a pick to catch the two small lock springs and draw them out through the rectangular cutouts in the
locks that secure the springs. There are no true spring guides or nipples. The springs are simply held behind the cutouts. The springs will
only come out in one direction towards the center of the frame, not the outside of the locks (not enough clearance). Then drift out the
cocking pin (#838), the trigger pin (#741), and the roller pin. Theres no obvious need (that I could see) to remove the release button and
the right lock from the frame unless the lock needs replacement.

HINT: Before disassembling the trigger assembly, be sure to carefully study, photograph, or draw a schematic of how the trigger spring fits
inside the trigger and on top of an interior portion of the frame. I chose not to remove the trigger, but the reassembly appeared
straightforward once the spring was correctly positioned.

HINT: On reassembly, be advised that replacing the two small lock
springs in their respective positions can be frustrating and time
consuming. Dont hesitate to muscle them into their cavities.

HINT: Leonard Joe advised me to set the NOS replacement main spring before I attempted to install it. This reduces the size of the new
spring and makes it easier to install (less force needed to compress it). I bought a 12" threaded steel rod that fit snugly inside the new main
spring. I attached a washer and a nut at both ends, then screwed down the spring completely and let it sit for 5 seconds. I then unscrewed
the nuts and the decompressed replacement spring was, indeed, shorter than before. It was, however, still a bear to get in the tube!

HINT: Tools needed at a minimum:
Padded vise; I used leftover carpet pieces secured with duct tape.
Thin, strong pick or one pointed end of a pair of tweezers (my
technique) to remove cir clip.
Correctly sized spanner wrench/other tool to remove the cylinder
Correctly sized spanner bit to hold the main pivot nut without
damaging it.
Flat-bladed and Phillips-head screwdriver.
Prying tool to spread apart the grip halves.
Drift punch to remove sear, cocking, trigger, and roller pins.
Plastic headed mallet.
Threaded steel rod, nuts, and washers to set main spring.
Dental pick.
Small thin-bladed jackknife to help muscle lock springs in place.

I hope these instructions will be of help to those who want to keep these fine all-American pistols shooting for many years to come.

Mike Van Winkle

This topic was modified 1 month ago by Garvin
This topic was modified 3 weeks ago by Citizen K


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