Ammo in a Fire

The April 2021 “Concealed Carry” magazine had a summary on page 12 of the recent NSSF look at what happens when ammunition burns. All the tests were done with paper boxes or cardboard cases of ammunition. Like many of us, I store my boxes in ammo cans, some plastic and some metal. Both are airtight. I’d be interested to see a fire test done on ammunition stored in a metal .50 cal ammo can. Anyone have info on that?


Unlike a “fireproof” safe (which can withstand a certain temperature for a certain length of time), neither of those are going to be airtight very long in a fire. Consequently, I can’t see there being any material difference between paper, cardboard, plastic, or metal storage containers. Besides, it’s the internal temperature that is the key factor, not the surrounding material.


A lot of snap, crackle, pop but no boom or flying cartridge’s. :man_shrugging:

From Hickok 45, pretty close to what you were asking.


The attached video is of a very comprehensive series of tests by SAAMI with the help of some pretty sturdy fire fighters. (I noted that they did NOT drop a case of rimfire ammo :slight_smile: ) . Includes a burn of multiple thousands of rounds in a semi trailer, and early on, shooting into boxes and cases and attaching a blasting cap atop a primer of one in a box of cartridges.

Although not addressing the storage of ammunition in steel ammunition boxes, the steel (e.g., .50 cal) ammo box will not retain pressure for very long, and as soon as compression is removed, the powder that burns most rapidly under compression will reduce its rate of burn again. So there will be compression only until the first round punctures or the pressure deformation compromises the seal of the ammo can. I’d like to see a test - the ammo cans in a fire might possibly reduce the random spew of projectiles (cases and bullets), containing some while not providing much in the way of direction.

Compression needs to be pretty high to get the bang you get in a firearm, and be sustained for the duration of the burn - that will not be the case with a thin skinned container.

The cartridges also don’t go off together - giving an increase until the container is ruptured as opposed to one sympathetic detonation.

I found this a compelling piece when I first saw it - dug it up for this thread.


SAAMI - Sporting Ammunition and the Fire Fighter

•Nov 2, 2020


If you look into the design of fire rated gun safes you’ll find at least one lined with Sheetrock. D SDs one are double lined. If you want a fire rated ammo can consider king it with Sheetrock (gypsum board)

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In the April 2021 issue of USCCA magazine, p. 12 has a good article on this, “Ammo & Firefighters: Hot Shots”. It warns about one in the chamber or revolver; I gotta think about this one. Food for thought. Feedback?:

It’s a valid point - if you cook off a cartridge loaded in the closed chamber of a rifle or pistol, the bullet exists the muzzle with all the normal energy - minus any reduction due to barrel deformation from the fire - if any. The steel used in firearms is good stuff. It will deform in a fire, but my guess is you’d cook off the cartridge well before such deformation occurs.

One of many good reasons to keep arms in a good gun safe, and keep them unloaded there… until ready to use. Fortunately, detachable magazine firearms allow the firearm to be unloaded but brought into action rapidly by seating a magazine and chambering the first round which is very quick.

What one actually does in practice will depend on the circumstances and planning for use.

  • How much firepower must be available on what time table? Seconds? Minutes? Tens of minutes?
  • Do I have a firearm outside the safe loaded and ready to go? -{{ “The pistol in the holster attached to the bed (or quick opening pistol safe) gets me to my long gun(s), gets me to fully armed for defense or egress.”}}
  • Are there other factors that dictate that I have X number of arms with loaded magazines (attached) and ready to chamber a cartridge? Are there reasons guns in the safe should be loaded? - Under almost any circumstances I can think of - the highest state of readiness allowable would be magazine loaded, chamber empty.

But generally, it seems like if they’re in the safe, they’re unloaded - unless the situation is extraordinary, in which case maybe they shouldn’t be in the safe at that time…

Other questions that came to mind:

  • Where is my gun safe? What would the effects of a fire be on the arms in storage there?
  • If my loaded arms cook off, what will be the consequences?
  • Reloading supply questions? Do I have a stock of black powder of whatever granularity? And there are laws on how much one can retain, and whether a powder magazine is required (however portable). Primers? Smokeless powder? (How much? How contained?) The black powder could prove interesting in a fire… depending on a lot of variables.

Thinking about a loaded revolver - a revolver cylinder chamber not aligned with the barrel would yield the same velocity as a zero length barrel without any constraint of the projectile… a lot of wasted energy, but just possibly some small increase in velocity above a cartridge cooking off without any containment at all. It would all depend on the cartridge and how the cylinder contains it. My hunch though is that the cylinder that is not lined up with the barrel, being smooth bore and very short if not zero, will not provide much in the way of acceleration.

Interesting to think through…

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Military ammo cans are designed to come apart if over pressurized (ie rounds cooking off inside) by the way the hinge is created. Once the “bail” of the can is closed the pins that hold the rear hinge (which the hinges themselves are reinforced) are designed to shear off. I have seen a can of .50 cal cook off following and IED hit and resulting fire. The results were unimpressive. Kind of a muffled "Wumpfff"with random pops and bangs when the rounds cooked off or the HEDP went off. I don’t believe any boolits or cases exited the can. 40mm is however a different story.

If you can get a revolver hot enough to cook off a round you one fast shootin’ sum gun with deep pockets and somebody filling a crap ton of speed loaders for you.

The only time I have ever seen a round cook off in a gun was on an M-60 after intentionally trying to break or jam the gun by running it hot. The gun was on a T&E mount and we got to about 3000 rnds and cut the zip tie on the trigger. with about foot of the last belt hanging out. It took about 20 seconds for the round to go off, 20 seconds later the next one went and so on till the belt was gone. I’ve heard about others but that was the only one I personally saw.



Why did y’all run it hot on purpose? I miss shooting M60s and M2s. Fun as hell.

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Appreciate it all you “Smokey The Bears”. Making me think of all those ideas and more.

It was the first Gulf war and I told the Marines they were stoopid to keep oiling the 60’s, SAW’s and 16’s in the desert. The 60 gun down was a proof of concept. Of course that went over like a lead brick, a Corpsman telling a Marine about weapons. Yeahhhhh my sh!t worked, theirs jammed and locked up. I used powdered graphite on my bearing surfaces and rotating twisty parts. I threw the 60 and my 16 into a vat of dry cleaning solvent (Varisol) and got ALL the oil out and dusted it. They both ran like their lives depended on it, squirt them with CLP and they would lock up most Ricky Tick. That said Jar Heads can be taught, by the time to 100 hour war was over and after a 3 day running gun fight all our weapons were up. Glad I had a good Master Gunz that would actually look at new info.



Interesting data on the ammo can - makes a great deal of sense. (40mm grenade rounds having explosive content being very different as you note).

Your cooking off a round in the M60 (and then the rest of the belt) due to sustained shooting and really heating the barrel is a good example - although in the fire fighting and fire related concerns the way the heat will affect the rounds outside the chamber and the round in the chamber will be different. I’ll guess that in a fire that cooks off a round in the chamber of a gun, the rounds in a detachable magazine will already have cooked off first, with no or very low velocity (as in the SAAMI video). So you only have the one round that’s really dangerous (one per loaded gun in the gun safe)

As a firefighter I’d want all my protective gear including face shield, but wouldn’t be harmed by the rounds in the magazine… the one in the chamber still being truly dangerous - and if one can get a good cooling spray on what has not already cooked off one should be able to bring the burning rounds down to zero. Interestingly, if there is a hot gun in a gun safe… you could still have a “late” cook off after suppressing fire around the safe. Heads up, firefighters…

@Clyde4 (First! Thank you for what you do!!!) You make an excellent observation especially for firefighters and emergency folks in general. The round chambered is the most dangerous if it can get hot enough. Now here’s another bit to chew on: Gun Powder and Black Powder (I’m not sure about Black Powder “pellets”). If you have no kidding FFF black powder and you stuff it in a tube and stick a fuze in it you have just made a stick of dynamite (albeit a poor performing one) but it will EXPLODE. Do the same with modern powders and you get a poor performing roman candle.

Now here is the part that worries me and should worry you. 10 lbs of modern powder in a 20mm/40mm ammo can that is NOT designed to sheer off. I’m not even good with powder in a 50 cal can as … well this is an open forum and the internet so I won’t say what you might could imagine given the above and previous.




Craig 6 - Good thoughts, black powder is an explosive differently than smokless, and black powder substitutes do behave differently. The GOEX material safety data sheet (MSDS) (link below) has some interesting figures for the different rates based on grain size.

Although smokeless powder can also be/become explosive - in sufficient quantity even uncontained it can accelerate itself (burning layer compresses layer below, pressure increases, rate of burning accelerates). Which is why recommended disposal by burning is only in small amounts - in fire safe and well ventilated areas… and I’m sure that depending where you are, just burning it in the “open” is probably an environmental infraction.

Primers are a different can of worms too. There are (I think) both federal and local regulations (depending on state) regarding quantities and storage of the different kinds of powders. Not yet doing very much in that line I never worried about it, although as I have a 2 1/4" bore Cohorne black powder mortar (muzzle loader) I did find that I was limited to 5 lbs of black powder at one go.

Note: There are good portable “magazines” available too for the dedicated reloader or cannon cocker.


GOEX MSDS for black powder (interesting data):

Pyrodex MSDS:

Hodgdon smokeless powders MSDS:

NOTE: I have to correct a misconception that I inadvertently created in the way I wrote my post: although I received some amazing fire fighting training in the course of service many years ago, I am not a firefighter, and except in training have not fought any fires, with one small exception when I pitched in with the local VFD against a grass fire. (NOT one that I had anything to do with starting ! :slight_smile: )

My hat is off to all of those who do the firefighting gig and don the gear and enter the inferno. It’s conceivable I might have been injured in the various training I received (it did get very hot), but when you go into a building “for real,” all bets are off and you just have no idea for sure what you’ll encounter. But it was nice of you to extend your thanks :smiley: We’ll just pass our thanks on to all those in the business past, present and future.

In my experience as a volunteer firefighter it tends to happen that if the fire reaches the ammunition no matter the containment it has the potential to ignite. To add, I’ve responded to calls that while being in route were informed by dispatch that rounds where currently going off.

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Lost my house to one of the wildfires. Had a 2 hour rated fireproof safe. it took less than 15 minutes for my house to burn down to the foundation. The safe and its contents were totally destroyed. So unless you have a small, not so hot fire, your fire safe is not really going to do anything. I think of them all now strictly as a security devices.

Regarding ammo, I had several thousand rounds. All the ammo cooked off relatively simultaneously (all about the temperature and flash point). A witness nearby said no rounds flew anywhere. With no enclosure, there are no speeding projectiles. Just like the the April 2021 issue of USCCA magazine article stated. A couple local firefighters said ammo was no big deal, but the thing that really scared them were the exploding propane tanks.

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The safe concept is actually based on the average response time of the fire department. The fire ratings are based on the temperature. I’m not sold on it either. I believe a metal gun case would be sufficient. I really don’t have a location for a strong safe,

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Watched a video where some guy dropped a handful of .22lr into a hot air popcorn popper. Was pretty uneventful. Some small dents. Can’t find the vid again, though.
Edit: Actually found it but yewtoob made it private because YouTube is run by evil people.