Pre war piston repair

[jonkem]

This is the damaged piston from a pre war militia Rifle and I could do with some knowledge from those more experienced with boingers

The assembly of the seal area is a mystery to me.
The seal fitting screw is sheared off so needs drilling out and I have no idea what the thread was and whether it should be converted to a modern thread after drilling?

Also the piston is 27.8mm dia at the head so what size seal would be expected for it?

Do you know how this was assembled? It looks like the latching rod passes through the piston and is threaded into the recessed nut within the piston head and the seal screw is threaded into the end of the rod. Does that sound correct?

Fingers crossed someone has knowledge of these

 

[ggggr]

This would probably be better off moved to the collectable section and you may have more joy there.

You will probably want a leather washer of 1 1/8 or make one. It does look as though there is a broken screw in the end of the piston (although some guns has a bit rivetted over------------and Im not saying the milita did) and you should be able to drill it out and tap it. Ive done that before on a Pre war Bsa butI tapped it to 2BA rather than the cycle thread that Bsa used. You could use BA or 4 or 5 mm Metric and CSK screw.