Round "cooking off" in the magazine?

[100]

To have a "cookoff" in a firearm, the mass of the gun metal in contact with the cartridge has to be large enough to attain and retain a massive amount of heat. That is why cookoffs are fairly common in air-cooled machineguns* and have been known in semi-and full-auto rifles, but are rare (if known at all) in handguns. Two factors are against it: 1) the mass of the gun is not enough to absorb and retain the heat needed, and (2) the magazine needs to be removed and replaced instantly, with an almost endless supply of loaded magazines kept ready.

To "cook off" a round, the receiver and chamber area of the barrel has to be fired almost continuously until it is near red-hot, but then has to be stopped with a round in the chamber and kept there long enough for it to attain firing temperature. A handgun "cooking off" from firing? I think I would call that one "busted."

[ryder021970]

I agree that without any more detail than what is available, we cannot really say what happened. A damaged casing exposing the powder and that powder catching on to some spark also sounds reasonable but the RO and shooter both claimed the round in the chamber was unfired. Perhaps a primer that was not seated properly caught on something and ignited.......

[bfoosh006]

I agree that without any more detail than what is available, we cannot really say what happened. A damaged casing exposing the powder and that powder catching on to some spark also sounds reasonable but the RO and shooter both claimed the round in the chamber was unfired. Perhaps a primer that was not seated properly caught on something and ignited.......

No offense, and not trying to be argumentative... but powder needs a "chamber" to "behave" like a propellant.
I don't think that a brass case could readily be a substitute for a chamber. In other words, the powder wouldn't burn properly or fully enough to create full pressure.

Much like throwing ammo into a fire, the rounds would fizzle rather then be allowed to produce peak pressure, primers pop out, and bullets pop out first... as opposed to when they are fully chambered, only then can powder create full pressure.

It is possible the primer detonated, ( IMHO, no matter how unlikely ) and popped out , while igniting some of the powder.. not enough to cause a full on kaboom, since again the powder wasn't in a pressure vessel ( chamber ) and while the bullet had no room to pop out, the case split... releasing pressure.

I suspect the whole story has become confused.

[Artiz]

If the bolt is out of spec or the headspace is improperly set, an OOB detonation is completely possible resulting in a case head separation, blowing out the magazine and (sometimes) destroying the upper reciever. I have seen it happen.

A case head separation is not an out of battery detonation. An AR can not fire out of battery. Full stop.

[P2000]

The theory still works even though there was an unfired round in the chamber. Like this, shot fired, bcg to the rear, empty is ejected, next round is fed as the round underneath gets lit.

I agree that without any more detail than what is available, we cannot really say what happened. A damaged casing exposing the powder and that powder catching on to some spark also sounds reasonable but the RO and shooter both claimed the round in the chamber was unfired. Perhaps a primer that was not seated properly caught on something and ignited.......

[Uni-Vibe]

I think cookoffs are myth. There's a video of a guy firing a m4 full auto, reloading as fast as he can. Rifle stopped when the aluminum gas tube melted. No cook off.

[georgeib]

I don't think the gas tube was aluminum.

[Iraqgunz]

Gas tubes aren't made from aluminum.

I think cookoffs are myth. There's a video of a guy firing a m4 full auto, reloading as fast as he can. Rifle stopped when the aluminum gas tube melted. No cook off.

[Belt Fed]

I'm thinkin a case rupture too, also if it blowed everything out through the magazine with no damage, wouldn't the floor plate be broken or even the mag since it slides on a lip? also on cookoffs, I have run a lot of rounds through full autos and never had one. Not saying it's not possible, just saying I've had them really hot before.