Quote Originally Posted by merlin5oaks View Post
So that would remove most of the radius,also what is the buffer washer for if you can remove it.I mean to say why use any way why not have a solid piston.,surely the tolerances are not that great or is it because the spring travel/bounce varies.After all we cant have the piston striking the cylinder transfer port.Aslo the question of the cocking arm 1mm tolerance to stop it hitting piston,is this not subject to wear given the force of the spring
This is discussed on another thread somewhere, I will try and find it. The buffer washer thing is curious, because there are other designs which don't have have and seem to be OK. I wouldn't be keen to dry-fire a BSA without one in, but then I don't dry-fire rifles anyway. The chamber has to be checked to make sure the front of the cylinder is square before removing the radius, but I am sure that this is what John Bowkett used to do on his 12 ft/lb Meteor conversions. The Bowkett Airsporter and Mercury conversions were long-stroked and were, according to the stories, almost recoilless and had very short springs. I will do some searching and see if I can find some more info.

There is also the PTFE piston head sold by T.R.Robb, which is supposed to give good results, but which can deform if the rifle is not used for long periods. John Budd got much better consistency with one in his rifle.