One thing we talk about at Appleseed (and just about any other reputable shooting course, for that matter), is the possibility of squibs and hangfires, and why you should take those very seriously.
Folks get the rough concept, but seeing it in practice is always a better reminder than just hearing or reading about it.
In the video below, we have a shooter in an IDPA match with a hat-mounted camera, and an excellent safety officer, who catches the squib round. Yes, it can happen just this quick and quietly, and you can easily overlook it if you aren’t specifically looking out for it.
Note that the shooter himself did not catch the squib: he missed the puff of smoke and did a tap/rack, thinking he had a jam. What would have happened if the RSO wasn’t very well trained? It might have ended something like this.
It is very simple: if you think you have a dud primer, especially in an AR-15, you keep your weapon pointed downrange to ensure that you don’t have a hangfire (with the round firing several seconds late). You then eject the round, and make sure all of it comes out, brass and bullet.
What almost certainly happened above is that one or both of the “bad primer” rounds had a primer but not powder charge, and their was just enough of a “pop” to move the bullet into the barrel. When he then chambered a round with a correct powder charge, it could not move 2-3 bullets, and the upper receiver blew apart. He was fortunate that he was not injured.
The hangfire is very dangerous, not for the action of the ammunition itself, but because of the possibly dangerous actions of the shooter who experiences one.
Free advice: never point a gun at your head.
It was only through blind luck that this guy didn’t paint the woods with his brains.
Another much less common problem is the double-charged or overcharged load, which due to a manufacturing defect, has more powder than the gun can fire safely, and it blows up. I’ve seen the results of precisely once, and we were fortunate that the shooter wasn’t seriously injured.
Anytime you pull the trigger and the gun goes “click, “puff,” or “boom” instead of “bang,” keep the firearms pointed downrange for a good ten seconds or more, then eject the round, verify that it is intact, and if it is not, immediately alert the range safety officer, unload the firearm and make it safe, and then get it off the firing line to be repaired at the RSO’s order.
The face you save may be your own.