Originally Posted by ginnz
youd almost think there would be a certain gain in power, as the physical size is increased, its gotta push more air, certainly being more powerful?
No, it's for filling longer barrels with enough air. Power has nothing to do with it. You'll actually lose FPS if you put a boreup kit in a short barreled gun, because the BB will leave the barrel before the piston has finished it's cycle, and it won't have all the power behind it that it would have had normally.