Replacement of a Feinwerkbau 65 Bumper Pistol seal

[45flint]

I just bought a 1978 FWB 65 with what I am sure is the original white piston buffer seal. It does not appear to be deteriorated but given its age you would assume it should be replaced? Is there as issue to continue to use the pistol as is and keeping an eye on it? I'm not going to put a lot of shots through it. The breech seal is blue, and I replaced the little knob stop. The gun is in just about mint condition so I assume it was not been shot very much.

[slow_runner]

I just bought a 1978 FWB 65 with what I am sure is the original white piston buffer seal. It does not appear to be deteriorated but given its age you would assume it should be replaced? Is there as issue to continue to use the pistol as is and keeping an eye on it? I'm not going to put a lot of shots through it. The breech seal is blue, and I replaced the little knob stop. The gun is in just about mint condition so I assume it was not been shot very much.

Hi flint. I would not hesitate to replace that buffer at the earliest time.
My FWB65 came with a broken detent slide due to that missing buffer.
http://www.airgunbbs.com/showthread....ht=feinwerkbau

[Benelli B76]

I just bought a 1978 FWB 65 with what I am sure is the original white piston buffer seal. It does not appear to be deteriorated but given its age you would assume it should be replaced? Is there as issue to continue to use the pistol as is and keeping an eye on it? I'm not going to put a lot of shots through it. The breech seal is blue, and I replaced the little knob stop. The gun is in just about mint condition so I assume it was not been shot very much.

You can check if the polyurethane has degraded by trying to mark or cut the surface with your finger nail or the tip of a screwdriver. Good urethane is tough and resilient and should not mark easily. The correct test is to use a Shore Durometer which are not expensive to buy. If you have the pistol already stripped I would replace it if you can source a new buffer easily.

Baz

[Garvin]

I just bought a 1978 FWB 65 with what I am sure is the original white piston buffer seal. It does not appear to be deteriorated but given its age you would assume it should be replaced? Is there as issue to continue to use the pistol as is and keeping an eye on it? I'm not going to put a lot of shots through it. The breech seal is blue, and I replaced the little knob stop. The gun is in just about mint condition so I assume it was not been shot very much.

It would be good to replace the buffer anyway for peace of mind. But, if it's really white or 'lemon yellow' rather than 'dark yellow', then it may have been changed already.

The fact the breach seal is blue supports this, but it's not conclusive since it's so easy to change the breach seal compared to the bumper.

Personally I think you could carry on using the pistol safely if it feels OK to shoot and you keep a close eye on the integrity of the bumper by shining a torch through the transfer port regularly to make sure it's not breaking up. It's not quite as crucial as the Giss guns, which can be severely damaged even if fired only once after the seals have perished, because on the FWB the chamber compression is provided by a metal piston ring. So if velocity is good and the pistol doesn't jar too much on firing, then it's working OK.

Then again, the other comments on this thread should be noted carefully.

[45flint]

Thanks so much for you comments. The pistol shoots perfectly and with velocity of 480 with 7 grain pellets. The white buffer seal is pure white not yellowed at all. I assumed any replacement would have been another color? I did just buy a seal kit from Maccari and have used the knob to replace the white bumper that was falling apart. The blue breech is fine. I have gone over posts on this site as to stripping down the 65 to replace the internal buffer. It certainly is not a simple project. I am mechanical and have stripped down a LP53 but this certainly looks more intimidating. I'm torn at this point really wanting to do it myself thus learning more about the pistol, and the concern I could screw up a totally preserved classic.

[Mark D]

Danny has this right. Yours sounds like it's shooting sweetly,so in the words of the wise "If it's not broke,don't fix it"

[Benelli B76]

Thanks so much for you comments. The pistol shoots perfectly and with velocity of 480 with 7 grain pellets. The white buffer seal is pure white not yellowed at all. I assumed any replacement would have been another color? I did just buy a seal kit from Maccari and have used the knob to replace the white bumper that was falling apart. The blue breech is fine. I have gone over posts on this site as to stripping down the 65 to replace the internal buffer. It certainly is not a simple project. I am mechanical and have stripped down a LP53 but this certainly looks more intimidating. I'm torn at this point really wanting to do it myself thus learning more about the pistol, and the concern I could screw up a totally preserved classic.

If you do ever strip it, make sure you put the shims that are held in place by the E clips go back in exactly the same positions that you remove them from.

Baz

[45flint]

I think I will heed the advice of "if it's not broke don't fix it" for now and keep my eye on it. I just got a replacement sight spring from FWB in Germany, awesome service, quick and free! The tab must have snapped off it was lying in the box and the sight could flop up. That should give me my mechanical fun for now. I much appreciate all the good thoughts. Great forum.