Ammunition 'cooking off'

[Vern Humphrey]

Vern, M2 fires from a closed bolt. Cooking off rounds is possible.

I have had cook offs with an extremely hot M16, but was using blank ammunition and 3 rd burst. I don't know if repeating the same procedure with live ammo would have changed the outcome.

Yes, the M2 is one of the machineguns that fires from a closed bolt. I commanded a Mechanized Rifle Company in Viet Nam, and each M113 had an M2 .50 Cal. I have seen M2 barrels get so hot they "drooped" from the heat, and even seen bullets tear through the sides of drooping barrels -- but never saw an M2 cook off. Admittedly, we cleared the guns when we stopped firing.

And the M16 also fires from a closed bolt -- run a few hundred rounds through on full auto and leave on up the spout, and you might well get a cook-off.

Been present for 2 different cookoffs in M240 MGs...and we were wearing them out and they were REAL hot....

The M240 fires from an open bolt. Where were the cartridges that cooked off?

 

[ambidextrous1]

I've seen cookoffs in the tripod-mounted .30 caliber light machine gun, which also fires from a closed-bolt position. This was after a few thousand rounds of .30-06, fired "in a bit of a hurry". The barrels didn't glow red or droop, but they were hotter than necessary to fry eggs.

I can't see that happening in a bolt-action weapon - but don't ask me to stand downrange when a round is chambered in a hot weapon.

 

[Vern Humphrey]

Where was the round that cooked off?

 

[isc]

I've seen a SAW cook off. The gun had malfunctioned with a round in the chamber (a link was hung up preventing the firing pin from hitting the primer). It cooked off and caused the bullet to squib in the barrel.

pretty easy to see how it could happen with a 240 too.

 

[Jeremy2171]

The M240 fires from an open bolt. Where were the cartridges that cooked off?

One the round was on the feed tray the other was in the chamber as they changed a hot barrel.

 

[Grunt]

Yeah, being an instructor, I've seen plenty of M-249 and M-240 machine guns cook off. What happens is when the shooter is firing along then a stoppage occurs. I teach them that it has to be an automatic instinct that when the guns stop firing, get the cocking handle to the rear sooner than ASAP. If they see ejection of a live round or a piece of brass, then rock on but if not, there may very well be a round in the chamber so in training which a hot gun is after the first round leaves the barrel, we will sand-bag the receiver, walk away for 15 meters for 15 minutes then come back after the gun has had time to cool, we'll clear the stoppage. However, in combat, a hot gun in machine gun world is a gun that has fired 200 rounds in 2 minutes and in the case of a cold gun (less than 200 rounds in 2 minutes) clear it out and then get back to shooting but with a hot gun, you have to do a "combat peak" and if there is a live round in the barrel, pull off the barrel (watching the front AND REAR of the barrel while you do this) put on the spare barrel and get back into the fight. The last time we went to the machine gun range with a class for both M-249 and M-240B, we had a cook off where a case head separated leaving the next live round in the first casing stuck in the chamber. We let it alone for 15 minutes and sure enough, it managed to get hot enough to cook off the round that was stuck in the casing that was stuck in the chamber so yes, cook-offs can and do happen. However, comma, pause for effect, if you are dealing with a bolt action or even a semi-auto that hasn't been subjected to a metric ton of mag dumps, the odds of a cook-off are pretty slim.

 

[Hoth206]

If you can work a bolt action enough fast and long enough to cook off a round...You've got more stamina in your right shoulder than anybody I've ever met.

My understanding is that brass is favored as a cartridge material because of it's ability to act as a heat sink which is then ejected and "cold" brass enters before the next round is fired. I can certainly see how a full auto could (and does) build up enough heat though.

 

[charcoalburner]

While anything is possible if the absolutely perfect conditions are present, I have never seen or heard of a round cooking off in a bolt action or semiautomatic rifle. However, I have never been one to test the theory by abusing my semi's like that. If you have fired enough rounds in any weapon fast enough to heat it up to the point of a cookoff, you have probably ruined your barrel. For me, the only valid reason to push this envelope in civilian life would be in a life or death situation or if you have money to burn.

P.S. To the posters who were throwing around "stupid" and "ignorant", not everyone is a "firearm expert" and firearm owners in general are not going to win any friends by being rude and snobby. IME, the world is full of people who lack the proper knowledge of firearms and firearm use. We as gun owners have a responsibility to help educate these people, not tear them down or alienate them. Off the soapbox and as always this is my 2cents and its worth everything you paid for it.

 

[isc]

ig·no·rant   /ˈɪgnərənt
–adjective
1.lacking in knowledge or training; unlearned: an ignorant man.
2.lacking knowledge or information as to a particular subject or fact: ignorant of quantum physics.
3.uninformed; unaware.
4.due to or showing lack of knowledge or training: an ignorant statement.

What part of that definition doesn't apply to someone that doesn't understand that you can't have a cookoff from slow aimed fire?

 

[AlexanderA]

Quote:
Actually any belt fed machinegun can easily be gotten hot enough, I have seen barrels glowing cherry red. But even that requires effort and usually several belts fired in a single burst. But the is no way it could ever happen in a bolt gun.

Except that virtually all belt-fed machineguns fire from an open bolt, so there is no loaded cartridge in the chamber, except for the brief instant when the firing pin is falling.

The Browning series belt feds (M1917, M1919, M2, etc.) fire from a closed bolt; this is one of their few weak points. The Israelis made a modification kit so that their .30 aircooleds would fire from the open bolt.

Having used Browning MG's in reenactments, I can say that using GI blanks gets the barrels considerably hotter than using ball ammunition. (The required BFA/bore restrictor doesn't allow the hot gases to vent out very well.) Worried about cookoffs, I made a habit of clearing the gun after every burst, and holding the bolt open by hand until the next burst.

 

[animator]

I can safely say that a couple .308 rounds thrown onto the coals of a 6-hour fire took around 2-3 or so minutes to get hot enough to cook off. I don't know the temp of those coals (hot enough to melt glass), but I'd be willing to guess they were significantly higher than a bolt action bore would ever see under normal circumstances.

 

[Vaarok]

The early full-power magazine-fed autoloaders, such as FN-49s, had occasional issues with cookoffs, being full-power rounds (large powder volume, large cartridge, less barrel mass/cartridge volume ratio), but it's a dump-several-magazines-and-then-maybe sort of thing.

With a bolt action rifle I concur it is very unlikely. But people have told me that it's impossible to get a manually-operated .22LR hot, and yet I've gotten my Marlin 39 to the point the fore-end was smoking.

 

[ceetee]

The question has already been answered, but I just wanted to ask: Why on Earth would you "plead" for your step-brother to load more than one round at a time? It's his turn, let him shoot in whatever way he feels comfortable. If possible, educate him to the fact that it would be really, really unlikely for a round to cook off in the magazine, and if he refuses to believe you, so be it. You can lead a horse to water...

 

[Phaethon]

The question has already been answered, but I just wanted to ask: Why on Earth would you "plead" for your step-brother to load more than one round at a time? It's his turn, let him shoot in whatever way he feels comfortable. If possible, educate him to the fact that it would be really, really unlikely for a round to cook off in the magazine, and if he refuses to believe you, so be it. You can lead a horse to water...

He was being a putz and trying to rush me with my shots, and then in turn took painstakingly long on his for no other reason than an uninformed fear.

Besides, it was the first outing with the rifle, I was interested in testing its reliability in all functions.

 

[Cop Bob]

OK, so we can take that as a NO...

A .308, (or any other caliber) bolt action rifle is not going to get hot enough to cook off a round..

What's with the name calling? I thought this was supposed to be the THR? He asked a question that HE did not know the answer too, and he trusted US to educate him... man, it juz ain't right... we were all there once, and in some ways still are, about more than a few things. I know I still am...

There was input about a pistol cooking off...

I was about ready to jump up and call BS on that one, Then I remembered an incident were a 1911 discharged COLD in a vehicles GLOVE Compartment.. safety on, slide locked, hammer still back. Primer had flowed back threw the firing pin hole in the slide.. There was a 78 or 79 dodge police car that needed some work done under the dash though.. Has nothing to do with a round cooking off from a hot barrel, but SOMETHING made it go off.. Speculation was it had something to to with a large electrical transmission line, but I doubt it...

So who knows, never say never... the surprising thing about guns, is, they will surprise you..