Converting the Webley Senior from a piston ring to a leather seal?

[felix gunner]

Cheers David, I'll take a couple and PM you.

You got any other thoughts on the whole power/PB ring/conversion to cup etc? You know more about these pistols than most!

What I might do is find an older scrappy/bitsa MK I or Senior to break up and mod the piston from that to try.

[Troubledshooter]

Cheers David, I'll take a couple and PM you.

You got any other thoughts on the whole power/PB ring/conversion to cup etc? You know more about these pistols than most!

What I might do is find an older scrappy/bitsa MK I or Senior to break up and mod the piston from that to try.

There are others on the BBS who know a lot more about the workings of Webley air guns than I do, as I seldom strip them. I occasionally get the inclination to have a play if I come across a problem, but that inclination doesn't occur often nowadays as I'm winding down my collection.
I've never attempted a piston conversion such as you are considering, as I don't have the facilities to carry it out. This lack of power has been discussed previously on the BBS and I think you have covered all the main reasons for it.
The old leather and brass breech seals can be a problem if they've been allowed to dry out, as can a tired mainspring or worn piston ring, so the only thing to try after thoroughly cleaning the cylinder etc., is replacements for all, and if that doesn't improve matters much, I don't know what to suggest.
I've probably got a used Senior piston amongst my spares, so PM if you want one.