I but the bullet and striped it myself, what a brilliant piece of engineering, I've never seen a,piston fit so well, and the
Piston ring seal is superb.
I found no grease on the main spring just a load of oil on the piston and the cocking arm screw had worked lose and was stopping the action recoiling properly.
Now Relubed properly it's shooting lovely, no felt recoil anymore, but still some spring twang which I'll put down to the spring not fitting the guide tightly. I may try a new spring and see what it like.