Pistol Piston Seal Material

[Cicero]

I am currently fitting a leather piston seal to my Webley Mk1 pistol. I have softened the leather, fitted it in the cylinder and now I am leaving it for a while to harden.

Just wondered if anyone has used an alternative material, turned on the lathe and recessed the centre to house the screw? I have some delrin rod which machines nicely but not sure if that would get too hot?

Any ideas?

[flatrajectory]

I am currently fitting a leather piston seal to my Webley Mk1 pistol. I have softened the leather, fitted it in the cylinder and now I am leaving it for a while to harden.

Just wondered if anyone has used an alternative material, turned on the lathe and recessed the centre to house the screw? I have some delrin rod which machines nicely but not sure if that would get too hot?

Any ideas?

No....delrin is not a good seal material and is prone to cracking in this application due to impact stress.
Ptfe is what Webley used on their later pistols and rifles, and I have used it with good results in rifles.
Pete.

[Cicero]

Thanks for that Pete. There is some on Fleabay for under a tenner. I'll probably get some and give it a go. I have a number of springer pistols so would be a good investment.

[TonyL]

Ptfe is what Webley used on their later pistols and rifles, and I have used it with good results in rifles.
Pete.

Mmmm....PTFE surged to popularity in the mid 80s as, back then, many rifles still had leather seals and the parachute seals were not too commonplace at that time. PTFE seemed to be an ideal material due to its "slipperiness", leading to less frictional losses.

Many still use the material today, and it does have its advocates.

HOWEVER....PTFE has no memory. Black Beard once provided a scientific explanation, going something along the lines of the molecules sliding over each other. This can lead to the seal increasing in diameter, then causing extra friction; exactly the opposite effect as desired. There have been cases reported of bulged cylinders, too.

Maybe, in a modestly powered pistol, taking less of a hammering from the spring and, I guess, lower temperatures, the PTFE seal would be more viable?

Is it worth considering a polyurethane or nylon material instead?

Or maybe a screw on head (aluminium or Delrin?) with a groove and use an 'O' ring?

[Benelli B76]

Polyurethane is the only material to use for friction and impact wear. Most manufacturers use it for piston seals today. I turn these out on the lathe to fit a lot of the oldies that had leather seals and it is much more efficient.Even used it on gingernuts 1905 Bonehill Brittania which now is an excellent performer. PTFE is a no no as it is malleable and will change shape. A lot of the other materials will crack under continuous impact.

Baz

[micky]

I am currently fitting a leather piston seal to my Webley Mk1 pistol. I have softened the leather, fitted it in the cylinder and now I am leaving it for a while to harden.

Just wondered if anyone has used an alternative material, turned on the lathe and recessed the centre to house the screw? I have some delrin rod which machines nicely but not sure if that would get too hot?

Any ideas?

l would stick with the leather as that is original with the pistol and it will last for years.

[Benelli B76]

l would stick with the leather as that is original with the pistol and it will last for years.

I would only use leather if you are a purist want the pistol to be as the old original. If you want performance and an easier fit with none of the preparation work, use polyurethane. That is why the manufacturers have progressed with materials that have superior properties.

Baz