Re: stock delrin bolt lubrication and slowing down ball fps
Do not lube/oil delrin bolts. If there are orings, then lube them but not the bolt. Scuffing will happen period. Only thing you can do is deal with it. I would look in the upper bore just to make sure there are no burrs.
Are you using Co2 or HPA? Co2 pressure will change with each shot, worse at higher rates of fire unless you let it stabilize.