Quote Originally Posted by look no hands View Post
The lump at the bottom of the piston is where the rod is attached to the piston, I had to build up the space around that lump so that the delrin top hat could sit on a flat surface, regarding the adjustable transfer port, I was once told by Tony Wall at SFS that he used to back the screw out so the TP was fully open and then tune the rifle from there, apparently you can then us less spring.

Pete
That's what i did to mine it shot much nicer & was without a doubt the most accurate & powerfull airsporter i ever shot. I'd still have it if it wasn't for dratted tennis elbow.