Ammo ‘Cooking Off’ in a Fire? Not So Much

Reader David Brown read a recent article at about a house fire that consumed the owner’s stock of ammo and supposedly kept firefighters out. As the article relates, “Flames cooked off an unknown quantity of various caliber ammunition in the home, sending slugs and shells flying haphazardly into the air.” Having read this kind of thing before, David needs to get something off of his chest: “I’m sure most of the intelligentsia is aware but as this story falsely states bullets shoot about when a cartridge is cooked off outside a firearm. Brass fragments? Hell yeah. But the only way a bullet will travel with any velocity is when it is in the chamber of a firearm. The brass is merely a gasket and will blow to pieces way before even the slightest amount of pressure is built to launch the projectile. I hear this myth way too often.” Feel better now, Dave?


  1. avatar Michael says:

    I hear this all the time. You mean Hollywood is lying to us?

  2. As a matter of fact the Army has IM (insensative munition) requirements for all ammunition. All ammo undergos various IM testing; fast cookoff, slow cookoff, fired upon, storage temp up to 160 deg F, etc. The Army requires that munitions be insensative so that they don’t blow in storage and when shot at. For example they want a grenade to go off only when intended. They have been designed so that if a grenade hanging off a soldiers chest is struck it does not explode.

    1. avatar Buzzy243 says:

      Hmm…5 seconds on Google yields thousands of documents pertaining to insensative munitions. Obviously quite a few people have worked on figuring out how to avoid the whole “bullets flying through the air” situation when ammo burns. Clearly the journalist lives in a fantasy world.

      My only question is what the hell do they teach in journalism school???

      1. avatar IdahoPete says:

        Sensitivity, tolerance for everything except conservative opinions, the values of diversity, and how to slant the news to benefit “progressives”. Also, how to lie with a pleasant smile on your face.

        A news story about guns is something with errors in it.

        1. avatar ScottA says:

          They don’t “teach” that. It’s implied.

      2. avatar Pascal says:

        In an homage to the Mythbusters video below

        “My only question is what the hell do they teach in journalism school???”

        They learn to “reject reality and replace it with their own”

  3. avatar jwm says:

    that’s why you keep your insurance up to date and with a reputable company. as long as my family is out of danger i would rather not risk injury or death to a fire fighter. i would rather err on the side of caution.

  4. Demolitions equipment is also designed for IM. C4, TNT, and military Dynamite are very insensative and will not react to bullets and fire. Commercial dynamite is about twice as powerful as military grade. It contains nytro glycerine, the army doesn’t like this because it leaks over long storage times and hight storage temps, and is too sensative for them. In a typical demo set up you have your higher sensativity explosives in small quantity in your initiator (trigger), connected to shock tube (or transmission line), then to det cord or high power blasting caps which then will set off your primary explosive. It’s a chain of events of descreasingly sesnative compositions.

    1. avatar Gyufygy says:

      I’ve heard stories of guys in Vietnam cooking their food over C4-fueled fires. Rip a chunk off a brick, put it under the pot, light it, presto-chango, don’t need no steekin kerosine.

  5. avatar Buzzy243 says:

    I always thought that “cooking off” was referring specifically to the situation in which a weapon (usually a machine gun designed to fire from a closed bolt) fires a chambered round without the primer being struck by the firing pin.

    Burning ammunition is just going pop.

  6. avatar Cellude says:

    Here you go

    1. avatar Michael B. says:

      What a ****ing liar.

  7. avatar ajax says:

    As someone who has had a birdshot pellet lodged in their cheek from a shotgun shell thrown in a camp fire…I can relate with the firefighters reluctance.

    And who wants to wager that any guns the homeowner might have in the house were loaded at the time, making a cooked off round absolutely lethal?

    1. avatar Nathan says:

      Meh. Like the OP said, the brass will blow as well, cutting the speed of any projectiles to a minimal level. Brass shrapnel flying around doesn’t sound like much fun, but these gents are wearing firefighter gear, which would almost definitely stop the brass and the low speed bullets.

  8. avatar Accur81 says:

    Ammo will cook off in a fire, and loaded guns in a fire can be lethal. If you want to bust the firefighters’ balls, go in there yourself and do a better job. Don’t blame me if you get a blazing hot brass case in your eyeball socket.

    1. avatar matt says:

      Don’t blame me if you get a blazing hot brass case in your eyeball socket.

      Firefighter helmets generally have face shields.

  9. avatar Ralph says:

    As a kid camping out with my peeps, somebody would throw a handful of .22s into the campfire every single time. Yeah, okay, we were stupid, but young ‘uns are supposed to be stupid, no? Anyway, catching shrapnel in the eyeball would have been messy, but luckily it never happened.

    FYI, the report of .22s going off in the campfire was something like a short string of standard-sized firecrackers.

  10. avatar J. Nelson says:

    About a year ago a family friend lost his home in a fire. Among his possesions was a pair of SKS rifles, an M1 Carbine, and an ammo can of miscellaneous ammo. All of which was stored pretty much at the epicenter of the fire. We found the ammo can while searching through the remains of his home. And while that ammo can was deformed and bulged out like you wouldn’t believe it only had two or three honest penetrations.

    Kind of drifting off topic here but it’s a real pitty that there’s no real way to reheat treat those fire damaged weapons. Especially that M1 Carbine. You can’t exactly get those as easy as you used to be able to. But all three weapons are pretty well toasted.

  11. avatar Jeremy L. Knauff says:

    We used to toss all sorts of munitions into the fire back in the USMC. No problems unless you got within a few inches.

  12. avatar jwm says:

    i’ve only been in one burning building in my life. that was enough to break me of the habit. hats off to the firemen.

  13. avatar Ozzy says:

    As an X firefighter I have been a housefire of a gun collector with all types of ammo and from firshand experience this story is false or its about some poorly trained firefighters the most it done to me and my partneer was chip the paint on our airpacks from the fragments of brass

  14. avatar Josh says:

    When i was in afghanistan in the marines, we had the not so smart gunny who wouldn’t let us smoke on post, because he said it would set off all the ammunition.

  15. avatar Southern Cross says:

    I’ve heard that the ignition temperature for primers is 50oC higher than propellant powder, so powder igniting will burn through the brass case before launching the bullet.

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