I picked up an older .25 S 510 a couple years back. $600. Sent it to Scot at MotorHead AG. He put a HUMA regulator in and lightened the hammer. I picked up an ultimate sporter and walnut thumbhole stocks. Scott knows how to fix AA S510's. 33 shots, at about 40 fpe, 3-4 % stdev. When it comes off the reg, it's absolutely predictable. It will put 71 pellets through the samme half inch hole at 45 yards. Great rifle. as accurate as my Crown and Impact. I added a Neil Clague LDC , and it is quiet.