Webley/Beeman C1

[Benelli B76]

I have only seen polyurethane used on these, as supplied by spares suppliers.

Baz

[Geezer]

I have only seen polyurethane used on these, as supplied by spares suppliers.

Baz

The original set up was a PTFE washer backed with a neoprene ring.

I believe later aftermarket replacements are polyurethane. See reference in the Knibbs ad:

http://www.airgunspares.com/store/pr...-Part-No.-V10/

[Benelli B76]

Yes, its because PTFE is a malleable material that deforms, they probably were quite ineffective early on in their lives. The properties of polyurethane are 100% better for piston seals. I think I have only removed 2 PTFE seals from rifles in the last 25 years. Not sure what the blue material is they used in old Webley pistols, that looks a bit like PTFE. Also not very impressive.

Baz

[evert]

The original set up was a PTFE washer backed with a neoprene ring.

I believe later aftermarket replacements are polyurethane. See reference in the Knibbs ad:

http://www.airgunspares.com/store/pr...-Part-No.-V10/

Webley also made their own polyurethane seal for the latest Vulcans and the other guns with the same cylinder diameter. These are purple, but look similar to the Knibbs seal. Jim Maccari and That Australian guy also make aftermakret seals for these guns.