Most of the high FPS pellet velocitys are achieved using very light pellets. No matter the rifle or pellet the best performance is FPS at or around 800 to 950 FPS. this is primarily due to the shape of the pellets and the exceeding of the speed of sound. When the pellet passes through the sound barrier there is destabilizing of the pellet once it drops back below that threshold on the way to the target there is further destabilizing of the pellet. Bob Sterne and Lloyd Sykes probably have a thread that can better explain this than me. The shuttle cock (badminton birdie) shape performs best at speeds below the speed of sound, that also makes the rifle more backyard friendly.In short these rifles perform better with heavier pellets and a little TLC to eliminate the issues like rough & heavy triggers which also hurt accuracy.