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Posted: 7/8/2007 6:45:29 PM EDT
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Is there a specific temp range that ammo will "cook off"? One of the guys at work had some ammo out in his vehicle today (upper 90's air temp) and thought he may have a problem. I told him that his ammo would not cook off, but it was probably not good for the ammo to be out in the heat like that. I kind of figured that fire safes have internal temp ratings of around 325 degrees plus or minus and doubt that his vehicle was going to get that warm. Was I wrong??? |
I have always read that for centerfire ammo the temp is in the 400F + range. 210F is not even enough to ignite paper, so I am skeptical of your numbers! Are you sure you don't mean 210C rather than F??? |
| My M16 will take 175 rnds from fast mag changes in 100 rnd beta C Mags before its hot enough to melt the gas tube, in that time a live rnd was in the chamber and even though it was hot enough to make the gas tube look like a pig pecker, it wouldnt cook the rnd off and it sat in there for a long while, as in atleast 5 mins. |
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And you probably never will. A cook off is what happens to a closed bolt weapon when a round sits in th echamber and acts like a heat sink. HM2's can cook off because they fire from a closed bolt, but open bolt weapons are not at risk. The Army did some testing a few years back with an M4. They put it in a rest and fired 30 round magazines as fast as they could change them. The barrel heated up and after about 450 rounds it drooped enough to cause a fired round to hang up and grenade the rifle. Sustained fire is 100 rounds per minute.
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I always get cook offs with the beltfeds, even had it run away after dumpin 2,000 rnds threw it non stop.
Cookoffs can also happen on belt-fed MG's. I've seen it happen in person just once in almost 5 years. Hell, we had to shoot M60s in pre-mob and we were laying into them like no other. Guys shooting 50rd bursts and whatnot and still nadda... |
? now i'm confused. |
How do you get a cook off in an open bolt machinegun? |
BE CAREFUL IN CLEARING THE WEAPON WHEN THE BARREL IS HOT, A ROUND MAY FIRE (COOK OFF) DUE TO THE BARREL'S HEAT INSTEAD OF DUE TO THE FIRING MECHANISM. DURING TRAINING OR ON A FIRING RANGE, AFTER THE WEAPON HAS FIRED 200 ROUNDS, ITS BARREL IS CONSIDERED A HOT BARREL. 2-24. IMMEDIATE ACTION Immediate action is action taken to reduce a stoppage without looking for the cause. Immediate action should be taken in the event of either a misfire or a cookoff. A misfire is the failure of a chambered round to fire. Such failure can be due to an ammunition defect or faulty firing mechanism. A cookoff is the firing of a round caused by the heat of a hot barrel and not by the firing mechanism. A cookoff can be avoided by applying immediate action within 10 seconds after a failure to fire. If the M60 stops firing, the gunner performs the following immediate actions. An effective memory aid is POPP, which stands for Pull, Observe, Push, and Press: a. Pulls and locks the cocking handle to the rear while observing the ejection port to see if a cartridge case, belt link, or round is ejected. Ensures that the bolt remains to the rear to prevent double feeding if a round or cartridge case is not ejected. b. If a cartridge case, belt link, or a round is ejected, returns the cocking handle to the forward position, aims on the target, and presses the trigger. If the weapon still does not fire, takes remedial action. If a cartridge case, belt link, or round is not ejected, takes remedial action. www.kelticklankirk.com/army_fm_3-22-68_c02.htm You tell me. The Army obviously saw fit to include it in the TM's what to do in the instance of a cookoff. 
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A cookoff in an open bolt weapon can only happen if you first have a failure to fire. A round on the feed tray will not cook off, ever.
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Thats akin to saying "a round in a magazine of an M16 will never cook off". Of course a round is going to have to be loaded to first start the cook-off process.... |
And your point is?
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He was probably trying to say Ditto (i.e. +1, agreed, I got the same, etc.), but spelled it incorrectly, as dido, which has an entirely different meaning. |
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You were saying "A round on the feed tray will not cook off, ever". And I was saying, thats like saying a round in a magazine wont cook off. Of course if a round isnt in the chamber, it cant cook off. 
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From the tone of some posts, it's obvious that some people don't know how belt fed weapons work. You obviously do,  but there are people who think that a weapon can get so hot that the rounds just start poping off from being in close proximity to the receiver.
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Haha, well thanks. I like to think I have just a tiny bit of knowledge of them.  I dunno how many times we assembled/disassembled them at Fort Sill and Ft. Irwin and then while in Iraq.
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What you had was a run on, not a cook off. M-60's in need of a rebuild are fameous for it. The only belt fed still in service that can cook off is the M2.
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