After about 200shots I got 726fps using superdomes and a sd of 5 for a ten shot run. This is on a chrony beta (with lighting fixture) that has given sensible results on other air and powder arms....I gather that is considered high, but the powerplant is well behaved (well, for an untuned cfx) and is not dieseling. A .177cfx after lots of shooting is giving me 855 or so for 8.3g pellets...working from memory on the .177.