Dude, you're scaring me. Bumping (for full auto) sounds like some creepy urban hoodlum car trunk-slang for something you probably shouldn't be discussing on this board. Or at least any board that has my contact info attatched to it. Pardon me whilst I edit my profile. Why would you want to take a stock mini and beat it that hard? Make that kind of racket? Draw that much attention? Go get yourself a Class 3 and buy a REAL full auto weapon.
bumping is where u stick your finger through the trigger guard and pull forward on the stock... the gun's recoil pulls the trigger. it allows a semi-auto to obtain a fairly high rate of fire. This is commonly done on semi-auto AK's.
This site does not condone illegal activity. 'Bumping' is not an illegal technique. However, it may cause some sticky situations, piss off other people, and as reloader indicates, why draw attention unnecessarily?
tuned, you may want to try this question on hardcoretalk.com