Anyway, back to my co-worker. The has a "Mac-10" I believe he called it and he claims they are quite prone to a condition called "slam firing" and it has even happened to him. He popped the magazine into his gun one time and the accursed thing emptied all the rounds, bullets whizzing mere inches from his ear! Now, I've known this co-worker for 20 years and I have no reason to doubt his honesty. He's quite serious about his weapons. If he says a certain weapon is prone to certain conditions (such as "slam firing"), I believe him. On the other hand, you guys don't know me from Adam, so I won't blame you if you think I am making up a fish tale.
The full-auto MAc-10 fires from an open bolt, which makes it vulnerable to slam firing - but that's an issue to do with the way the firing mechanism and magazine are set up, so it might go off when reloading, or burst-fire when trying to fire single-shot. It's *not* the same as going off when dropped - that's not what "slam-firing" means.