Mystery piston

[ggggr]

Ok--I cannot do pics (no camera etc)-------------but I received a piston today that is similar in style to a Webley Junior but is larger in diameter and shorter.
There is no cocking slot or rod in the piston or a hole for a sear or trigger to go, other than a ring---so very similar in style to the Webley.
It is 755thou in diameter and 3inches, 066 thou long, without the piston washer.
The bearing surface at the front is 325thou wide and the one at the rear 256thou, which is about twice the width of a Webley. The front of the piston is tapped for a screw that seems closer to 3BA than 4mm.
I was wondering what this was off
It is not ringing any bells with anything I have stripped-----------Relum, Slavia ZVP, BSF 20, Diana Modell 5 etc.
I was thinking maybe a small Gem and somebody has tapped the piston for a washer.
Ring any bells with anyone?

[ggggr]

Has anybody got any thoughts on the mystery piston?

[Geoff555]

Hi thoughts, yes, but of no help I am affraid. I have a small gem but the piston is bigger.
Length 3.468"
Dia. rear. .915"
Dia. front .944"
Rear bearing width .21"
Front bearing width .237"

I have nothing else in springers that is smaller than about 1" diameter.
Sorry.
Cheers.
Geoff.