I'm sure if he had a glowing barrel, inserted a fresh mag and walked away, he would have cooked off some rounds. Instead he was quick enough they didn't go, which is good for him. That plastic face shield would not have been sufficient had one or more gone boom in the mag. Not an especially clever thing to do, and no "don't try this at home folks!" warning.
Hmm, I was curious, so I tried to figure out how hot the barrel got and what it'd need to be for the ammo to go off.
Seems to me that roughly where the handguard was is the bit that got the hottest at around 900-1000 rounds, and that bit got to maybe 1050F/560C judging by its color. Not the most accurate way of measuring, I know, but don't see a better method.
Now, it seems like the parts that are connected to larger amounts of metal heat up slower or are cooled down quicker, so it's just that one bit that's only in contact with air that gets real hot, the rest seem to stay relatively cool and I mean, sure, some of the barrel is kind of just hidden behind other stuff but judging by how quickly the part that's visible changes color back to black, I'm not entirely convinced that even the chambered round would just go off. Let alone the ones in the magazine.
Well, having made a dumb picture I now realize that I was thinking of the gunpowder going off, which requires 800F/430C, but the primer could actually go off at much lower temps at 320F/160C. The primer is 1.5 inch / 39mm further away though. Idk, that heat is going to dissipate like crazy fast though when the gun isn't fired, it even went way down the moment the guy slowed down sometime after 1000 rounds.
I mean, I wouldn't be too surprised if the one in the chamber went off, but there is no way the ones in the magazine would. The one in the chamber going off would of course chamber the next one, and that might still go off after a while, but even then I don't see it firing more than one or two on its own.
