Originally Posted by Styrak
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.
ahh, yeas. makes 100% sense.... thanks for the info!