Canadian Airgun Forum

I am often asked by friends and acquaintances if a certain 10M air rifle or pistol is a "good deal", and the first question that I have to ask is, "was it recently serviced?". The vast majority of the 10M guns that are around 30 years old are almost definitely in need of service, and that should be figured into the price paid for such a gun. While most sellers will insist that the gun "shoots fine" as is, they really have no concept of what is inside, and if any damage has already been done. Many of these match rifles and pistols utilize metallic piston rings, so while these will maintain compression, they will not offer buffering protection of the hardened steel components that make up the rest of the powerplant. If these "soft" components are allowed to deteriorate to the point of metal to metal contact within the gun, major damage could result, requiring costly repairs.

In this particular example, the gun is an FWB 80 match pistol, and it was indeed shooting fine, but the firing cycle was noticeably harsher than it should have been. Upon disassembly, the reason was obvious - the piston buffer had deteriorated to a waxy consistency, the piston bumper had fractured around it's full circumference ready to break apart, and the breech seal had begun to deteriorate from behind. Small bits of the piston bumper had to be getting blown out the barrel with each shot, as there were no signs of the bits within the compression chamber.

In the pics below, the top left pic is what is left of the piston damper after removal from the front of the compression chamber. The top right pic shows what is left of the piston bumper after removal from the front of the piston - note what appears to be a ring just in from the outer edge of the bumper - that is the fracture line noted in the paragraph above. The two bottom pics show the breech seal - even though it is of the blue coloured synthetic, it has begun to deteriorate, and oddly, the back side is beginning to break up.



In this next pic, you can see what these components are supposed to look like. The pic shows two comlete sets - ie - to do two guns - but shown here just for different perspectives of the pieces. Left to right - piston damper, piston bumper, and breech seal.

PART II - The Mainspring(s)

I figured that I would just add to this thread, since the topic is pretty much the same.

A friend of mine recently purchased a very nice Daisy/FWB Model 300S, and since it was unknown if the gun had been serviced recently, if at all, since new - he took my advice, and had me check the gun out. The first thing thing that I noticed was that there was absolutely no tension felt when closing up the cocking lever, so the breech seal was obviously kaput. Yup - it was one of the very old, whitish coloured ones. Upon firing, the cycle was noisy with a distict buzz - not good. the velocity was down - only shooting at right around 500 FPS.

Upon opening up the gun, it was immediately obvious that the gun had one broken spring. The broken piece had wound itself into the rear of the remainder of the spring, causing it to bind on the spring guide, and badly canting the spring beyond the guide. It was not until the parts were all fully de-greased that I noticed that the spring had also fractured a few coils forward of the broken area, no doubt caused by the added stress of the cant induced by the previous break. It is surprising indeed that the gun was still producing the velocities that it was with the spring in such bad shape. I suspect that it was only a matter of a few more shots before the fractured section failed completely.

The pics below show the broken spring with the area of the fracture circled in red, and then a couple of closeups of the fracture. The other spring in the counterwound set appears OK, but will obviously be replaced since it will without a doubt be very near the point of fatigue/failure as well.

Kinda neat to see how the old seals and springs deteriorate over time. Thanks for posting.