Hi Ron,
I thought that maybe that was the reason. However, a few years back I changed my old leather headed piston for the newer synthetic piston and put a nice new piston head on it and changed the spring. It kicked like a mule, truely hateful! I put the old spring back in and it is much better now so the replacement spring wasn't well matched to the gun. That said, I still think that it shot sweeter with the old leather washer. Unfortunately I've mis-placed the old piston so I can't re-fit it and compare it. I'm not sure exactly what power level it's running at because I don't have a chrono but from experience I'd say less than 11ft lbs and not half refined enough for my liking. Maybe I should just buy a stage 1 kit from Venom and see what that does.

Andy W