Take a look at this bump firing, it looks like he has it shouldered and it looks like all his shots are within a pie plate or so. That's pretty darn good:
http://www.youtube.com/watch?v=PVfwF...eature=related
I've seen people bump fire from the shoulder just like this video but without a rubber band, and their stance and rifle seem very stable. I'm not sure why people are condeming bump firing and then in the same paragraph approve a full auto class 3 weapon. Either one will draw the same amount of attention. I suggest getting a class 3 suppressor (silencer) before bump firing to keep the attention down. If you practiced enough and were really good you could keep your bump firing to three round bursts.
I agree that a round can't go off out of battery unless you have a defective rifle / firing pin.
Anyone who says there is no use for full auto fire hasn't been in combat with 10 guerrillas charging you at the same time (or 10 terrorists with swords).
As far as a waste of ammo, if you cast your own bullets and reload you could probably reload 1000 rounds for around fifty bucks.