by Nocte » Wed Sep 10, 2008 6:53 pm
Assuming you're talking about an Armalite, the Classic Army ones have a one-piece style that doesn't wobble. TM and others make a less durable three piece outer barrel that tightens down with set screws, and these screws aren't very good at holding on very tight, and you'll have a little play between your foregrip and upper receiver.
It doesn't affect anything inside the gearbox, though, if that's what you're asking.