Got my FX IMPACT a few months and just started to adjust it the past couple days. Seems to like the heavys at about 835 fps. I have a pellet trap set out at 57yrds. Heres my best groups so far....One is 11 shots under a dime the other with my finger was 4shots and i was afraid ti take a 5th shot lol. Shooting off a plastic folding table,atlas bipod,hawke eclipse 6x24 scope.