[jboot]

"The ammunition exploded in the chamber."

Well, DOH! Next they won't want ammo that actually explodes.

It sounds to me like someone was firing with a bore obstruction. Maybe a couple of cadets left cleaning rods or boresighting spuds in place?

[dep]

your implication is dead wrong. the powder in a cartridge does not explode. it burns. occasionally, as when there's a powder charge that is smaller than the case, it does explode -- the phenomenon is called "detonation" -- and usually it damages the weapon and sometimes the shooter. you do not want the powder to explode. you want it to burn. the terminology is correct and the implication you make is a little bit wild-eyed and entirely incorrect.

[DBrow]

I had a case failure in an Armalite, I don’t know if the round even chambered. But rat-tat-tat-POW kching whizzz!

The mag was belled out at the bottom, all the rounds had been pushed right out through the bottom, looked like the round at the top had ignited when the one in the chamber went.

The charging handle on the Armalite went flying to the right.

The bolt was a loss, extractor bent, and it could not be disassembled.

Nobody got hurt, luckily, but having that happen in your arms is a high-adrenaline event.

We think that some of the ammo had failed-to-feed before but got put back in the box, not a very good idea.

[fireforeffect]

Or wrong caliber bullets.

Or incorrectly seated bullets. A bullet that is seated too short or too long can cause excessive chamber pressures. In a best case, like this one, it only results in a ruptured case and some damage to the rifle. Worst case is a breach failure, which results in bits of metal flying around the room.

Military firearms are designed for this to happen. I have seen the barrel group of an M60 MG go flying down range when a squib got just past the gas port and the following round sheared the barrel. The barrel was designed with a failure point just in case and functioned as designed. No one was injured, only soiled.

[Tolsti2]

Is this for real? Do we have any source?