so far ive opened up the transfer port, the barrel and the valve port to .153.. that did nothing.. Then i wet sanded the lead in on the barrel , that made cycling a dream.. Ive been messing with hammer springs, but theres really no room at the back for binding or coiling up, so i ground 1/8th inch off the hammer so the sear engages a bit earlier.. I tried the 760 and disco hammer springs, Yes they work but the length isnt right, so I just ordered a paintball hammer spring that Im familiar with and can be cut to length.. ( explaining the hammer spring constriction is hard unless you have one.. HERES THE VALVE pic
Anyway.. what I did was measure how much preload was on the valve stem.. Then , to add volume and reduce preload all at once i simply chucked it in the lathe, took a mm at the back wall , reassembled , and repeated till i felt a reduction in force to open the valve.. SO far soo good and I can still go further.. I did not have a good spring to substitute the stock valve spring , but when I do , that will be a huge gain.. I then proceded to part off most of the valve threads, they are not part of the seal , and again , a tiny gain in volume..
My stock numbers were 605 peak , and quickly dropped off to 585 ish for the rest of the usable string.. I just shot a crosman premier at 667fps for the first shot , and then leveled off in the 640s.. So im making progress. With the lighter valve stem spring , and longer hammer spring ,. I should be able to reach my 700 goal.Oddly , shot count hasnt changed noticeably , well yet'
.153 port job doesnt take much material , maybe .020