Loose Round Explodes In The Pocket

Practical Applications posted a rare occurrence and managed to capture it on video. A shooter was shooting an indoor match when a loose round exploded in his pocket.


Watch his left pant leg immediately after his 2nd reload!

During last night’s Monday Night Challenge at Caswells Shooting Range we had what seemed like a spontaneous discharge of a loose cartridge in a shooter’s cargo pocket. As the RSO and Match Director, I heard the noise but when I looked down I saw the base pad sliding off a magazine he had dropped, and thought it had something to do with that. After his last 2 shots we cleared him out and I went to inspect the magazine when all his other rounds came pouring out of the new hole in his pocket. That’s when we saw the exploded casing and perfect bullet on the floor and then took 10 minutes to investigate what happened to ensure it didn’t happen again. No primer was found for us to inspect. All the rounds that fell out of pocket were scalding hot to the touch. The ammo was factory grade ammunition, and the manufacturer is being contacted by the shooter.

We came up with 3 possible scenarios.

1. Freak ricochet from a 2″ angle cross beam on the very back of the backstop flew back and set off the round. Even though we were past the standard 10 yards away from hitting any steel.

2. Something possibly set off the cartridge in his pocket.

3. Spontaneous detonation.

What do you think happened?

In closing, we’re making the appropriate changes to ensure if it was a ricochet that it doesn’t happen again. And it is never a great idea to keep loose ammunition bouncing around in your pocket.

Share this post and let us know what you think set off the cartridge.



Here is a photo of the cargo pocket.

Here is the exploded casing.


I have heard of similarly unbelievable occurrences. A friend was competing in an USPSA match and when he finished he performed the “unload and show clear” action. The unfired round ejected and he watched it fall to the ground. It fell and as soon as it hit the ground it exploded. This was not a delayed detonation. He never pulled the trigger and the firing pin never touched the primer. They think the round fell just right and landed on a rock which set the primer off.

I heard of another instance where an empty casing ejected and landed on an open box of ammo. The rounds were in the box primer up and the empty casing landed and set off one of the primers.

These stories sound like fantasy and yet the people who relayed these first hand stories are people who do not resort to exaggeration or fabrication.

Have you experienced any rounds that seemingly detonate for no reason?

Nicholas C

Co-Founder of KRISSTALK forums, an owner’s support group and all things KRISS Vector related. Nick found his passion through competitive shooting while living in NY. He participates in USPSA and 3Gun. He loves all things that shoots and flashlights. Really really bright flashlights.

Any questions please email him at nicholas.c@staff.thefirearmblog.com


  • scott loddesol

    I’ve had old ammo cause brass to swell but always in the gun. looking at the shell it looks like the powder detonated first but that shouldn’t be possible unless there was a hairline crack in the brass. Ejected brass ends up in places it shouldn’t.

  • I’ve never had rounds detonate “for no reason”, but I have seen a .308 cartridge roll off a table and detonate when it landed primer-down on a rock. Hopped in the air like a firecracker, brass split open like a microwaved hot dog from the neck to just past the shoulder, bullet was found a few feet away completely unmarked, primer may very well still be in orbit. Other people were firing at the time, and the shooter at the table didn’t even notice.

  • BattleshipGrey

    If it was a ricochet (even just a fragment), shouldn’t there be a small entry hole somewhere on the shorts?

    • Nicholas C

      It could be eradicated by the round exploding. The entry hole could be where the exit hole is.

  • GPSrulz

    4. Electrostatic discharge (ESD)

    • Phillip

      I was thinking the same thing.

    • TechnoTriticale

      ESD seems the least likely (until polymer ammo becomes more common). A metallic cartridge, metallic primer, and metal bullet form a Faraday cage, which prevents external fields from developing potentials inside the cage.

      I’m intrigued by: “All the rounds that fell out of pocket were scalding hot to the touch.” How is that possible without setting fire to the pants?

      • flyingburgers

        Smokeless powder itself is not naturally conductive, so it can form a charge from shifting. Agents are normally added to dissipate the charge, but if there was a problem in manufacturing, it could happen. The powder manufacturer is supposed to have a specific ESD test machine to quantify this.

        • TechnoTriticale

          re: …Smokeless powder itself is not naturally conductive, so it can form a charge from shifting.

          But can it build up sufficient potential inside a compact fully metal environment? If mechanical static charge formation was a material hazard, I’d expect we’d be reading about it at least as frequently as we see cartridge incompatibility kaboom reports.

          There are lots of scenarios that subject cartridges to shakes and thermal stresses far greater than in this range exercise.

          That said, manufacturing defects need to be investigated and ruled out here. I won’t bet against your theory. They also need to scour the range for the primer.

          Another point the TFB author might have made is to emphasize just how surprisingly little damage is done by unconfined cartridge detonations. Bullet movement is the least concern.

      • Edeco

        I’m wondering tho if there were an insulating coating on the bullet could there have been potential between that and the case? Admittedly ‘leck-trickle stuff isn’t my thing.

        • TechnoTriticale

          re: …if there were an insulating coating on the bullet…

          Polymer bullets already exist (e.g. ARX). We might then expect the first instance of an externally-induced ESD to involve a poly, or the even older Nyclads. The present case appears to be a standard FMJ, so odds favor the explanation being elsewhere.

      • Mystick

        Faraday cages still conduct surface current, and if what they are protecting is in contact with them, it will not be protected from electrostatic energy; as is the case with gun powder in a conductive cartridge.

      • nonobaddog

        All the powder in the round that went off was burning in his pocket.
        There was no chamber to contain the burning so no huge pressure built up, just enough pressure to push the bullet out of the case. Then there is just some gunpowder burning in his pocket. That will heat up anything in the pocket with it.

  • Giolli Joker

    Everything seems incredibly unlikely, but to throw in another possible scenario:
    one round was caught somewhere up in the pocket by the lid/a bend in the cloth, with the shooter movement it dislodged with the FMJ bullet itself falling head on straight on the primer of a round in the bottom of the pocket, bullet down.
    The rounds should be nose heavy so the scenario is possible, although I’d never believe that a fall of around 4″ would give enough energy to set off a primer.

  • Bucho4Prez

    That’s what one gets for owning cargo shorts…

    • A.WChuck

      You are on the wrong TFB. The Fashion Blog is two doors down, on the left.

      • PK

        I do seem to recall a MDS review here not too long ago…

  • Martin Grønsdal

    isn’t this why tubular magazines and spitzer-bullets are a no-go? bullet hitting the primer? in a pocket, tossed arount, even rounded bullets may set of the primer.

  • AmmoMFG (Drew)

    I’ve seen this happen first-hand. Someone had a ziplog bag full of blanks, and was tossing it (not throwing, tossing) the other person missed, and the bag fell to the floor followed by a very loud POP and blanks flying all over the shop. The rim of one casing hit a primer with enough force to set it off, and Kaboom!

    Modern ammo is some really amazing stuff, it’s only 4 components but an absolutely incredible amount of technology, trial and error, and experience that goes into designing and making ammo. (I should know, I do it for a living)

  • USMC03Vet

    What happens when you load Mexican jumping beans instead of gun powder, Alex.

  • Unsooper

    Hot cell phone.

  • Jordan Bowles

    What does the primer or primer pocket look like?

  • Independent George

    #2 seems most likely – something struck the primer while in the pocket.

  • Phillip Cooper


    Definitely aliens.

    • Dougscamo

      Russian aliens at that!

    • Spencerhut

      Idiot . . . no way aliens are not real . . . unless this happened in California, that place has all kinds of aliens. It was the Russians

    • This is why you don’t put your aluminum hat on inside out, the rays get focused farther down your body thus heating bad things like nuts and bullets in your pockets.

  • Gun Fu Guru

    I’ve had this happen to me once. I was carrying three factory magazines with factory ammo in my pocket. I didn’t notice anything was wrong until the magazine wouldn’t seat.

  • Risky

    If a single, loose round detonated in his pocket that alone should not be able to generate or transfer enough heat to the other rounds to make them ‘scalding hot’. This leads to me to consider that some freak heating occurrence (exothermic chemical reaction/electromagnetic induction,electrical current) happened to the single cartridge. However, that’s almost like saying it was magic without any other evidence. I did find this blurb from a forum regarding cook off temperatures:

    “In his book “Gunshot Wounds” Vincent Di Maio describes various
    experiments where ammunition was heated in ovens. He says that .22 long
    rifle cartridges detonate at an average of 275F, .38 Special at 290F and
    12 gauge shotgun shells at 387F. The interesting thing about these
    furnace experiments was that in all instances the cartridge cases
    ruptured, but the primers did not detonate. In fact the primers were
    removed from some of the ruptured cases, reloaded into other brass and

    Since no primer was found, it seems like a cook off as described by this second hand accounting of the Di Maio book is unlikely. It could be possible that the heat generated was localized to the primer itself rather than the rest of the cartridge, leading to the primer’s detonation before the powder charge. Without something else in the pocket to generate that kind of small, localized heat source I still don’t see that as possible (basically would need to be a plugged in soldering iron in his cargo pocket). Further from that same post and book:

    “In rifle and handgun cartridges where the flame was applied to the base
    of the cartridge the primers always detonated but the powder only
    ignited in half the cases and in those instances the cases did not
    rupture but the gas was instead vented through the primer hole.”

    So it seems that we not only have a missing primer but a ruptured case… further evidence pointing away from a ‘magic’ localized cook off. I think a freak ricochet seems the most likely culprit in lieu of other evidence… but I can’t get that ‘scalding hot’ observation out of my head. Sounds like we need to call Mulder and Scully on this one.

    • Uk bloke

      I agree that the scalding hot cartridges seem unusual. A single cartridge detonating could not heat the others up to any significant degree so how did they get hot?

  • Qoquaq En Transic

    Did the guy have a battery or cell phone in his pocket?

    • Dougscamo

      Samsung Galaxy….

    • Kodi

      Good question.

  • PK

    “when all his other rounds came pouring out of the new hole in his pocket. ”

    He had a bunch of other loose rounds in the same pocket. It happens, another cartridge’s rim/nose hit the primer of that one.

    • phuzz

      This is definitely the simplest explanation.

    • Dakota Raduenz

      I’m agreeing with all the “battery” comments, myself. I did that in a non firearm context and boy was my pocket hot. Like Arizona at high noon in July.

      • AlDeLarge

        I’ve made the mistake of putting a 9 Volt in a pocket with change. I think a battery set it off, especially with the mention of all the other rounds being so hot.

  • Jerry_In_Detroit

    Remember back in my cop days when an officer dropped a 9 volt battery into the same pocket with loose .38 rounds and had a round go off.

  • arpad1000

    “All the rounds that fell out of pocket were scalding hot to the touch.”

    To me that says “battery”. What else could heat “all” the rounds in the guy’s pocket but a battery discharging through cases and heating them till they became unstable?

    • AlDeLarge

      That was my first thought when I read that part, too.

    • Sausage

      My thoughts exactly.

  • Look at the timing, not a ricochet. Loose rounds in pockets just happened to get lined up wrong.

    • Dr. Longfellow Buchenrad

      When the ammunition aligns…

    • John

      Was going to say the same thing, I’ve been hit by a number or ricochets and they are almost simultaneous with the shot.

  • DropGun25

    This is interesting. I know a colleague who had some loose ammo in his pocket and then dropped a battery in there by mistake. After a few days he hung up his pants and we heard a “boom”, came back to find the battery set off one of the loose rounds and put a hole in his pants pocket…

  • Marc

    As a young man, my pistol was known to detonate a little prematurely……

    • Thomas Oakheart

      Atleaset you are humble, I would call mine a 12ga full choke shotgun.

  • Jack Cash

    At about 38 seconds into the video something lightly strikes the shooter on the left hamstring (actually strikes the leg of his pants) then falls to the floor.

    • Anonymous

      This. I’m going with ricochet here. The timing is so close to the previous shot, with just enough delay to account for the time of flight of the slower ricochet fragment, and the audio. The dropped object might just be the bullet and casing, but it looks like the pocket is also being knocked inward at the same time.

      • Rob-L

        It definitely appears that something pushed the fabric inward from the rear doesn’t it?

  • RGary Driggers


  • India_Actual

    I bought some 1950s 8mm bandoleers stacked in a cardboard box (~250 rounds). After opening it, I found that one round had exploded. That round was in the middle of the stack, so I know it wasn’t caused by something hitting the box. No nearby rounds had exploded, though they were all seriously dented. I still have no clue what happened.

  • Blake Bass

    To answer what seems to be everyone’s question, no I didn’t have anything else including a battery in my pocket. I had just loaded down my magazines to the requirement of the stage and threw them in my pocket

  • Just Say’n

    I USED to store extra shotgun shells in the hollow stock of my NEF 12 gauge single-shot shotgun. One day one of my scouts was using it to shoot clays and he screamed “My EYES!!”. I found burn marks on his cheek and around the seam between the stock and the action. I emptied the stock and found one exploded shell among the five or six others in there, lots of #6 shot, a wad, etc. I think the primer contacted the end of the bolt that protrudes into the stock cavity under recoil. Scout was OK, but scared (me too!).

  • Cory Carlson

    How many rounds were in his pocket? Is it possible that if there were loose rounds in his pocket that the tip of one bullett hit the primer of another bullett in just the right way? As far as the bulletts in his pocket being warm to the touch I would say it’s kind of like when you do a penetration test and shoot a round into a fully loaded mag, the heat has nowhere to go and the other cartridges get warm. Now would a pocket act the same way? I have no idea, some forensic scientist will look at the pictures, slow the video down and give us an answer eventually.

  • DanGoodShot

    Definitely not from a ricochet. Too much time between bang of the gun and bang of the pocket. There is a thing as overly sensitive primers. It does not happen often. Its when the anvil get set too deep into the primer cup.

  • Kenneth Schmidt

    I think its loose primer powder on the outside of the primer pocket on top or near the primer itself, that stuff inside the primer is dangerous. I used to work for one of America’s largest ammo manufacturers as a contract employee. We didn’t move primer powder, even inside a truck, if there was a thunderstorm within 25 miles.

  • Ed Forney

    I must be blind. Don’t see anything.

  • Isa Akhbar

    Ricochet…something hits his cargo pocket in the video.

  • ozzallos .

    Possible that another bullet bumped the prime hard enough to set it off since he had a number of loose rounds in his pocket? Now these aren’t spritzer point rounds, but it’s same concept as to why you don’t stack them in lever guns. Now, I didn’t say it was likely…

  • shooter2009

    How about a photo of the primer?

  • George Harris

    Bottom line, Sh#t Happens. It’s life and Life Is Stranger Than Fiction. Move on, nothing to see here. 😉

  • Kodi

    I”m curious as to why the loose round that were in the cargo pocket were ‘scalding hot’. That doesn’t seem right. Why were so many loose rounds in his pocket, where were they before that and how long since they had been put in his pocket?
    Had he emptied a magazine or ammo box left in a hot gun, in the sun or other heat source before putting them in his pants pocket?

  • Obi Sean

    Was there a Sig P320 in the room? LOL

  • Joakim Wilén

    Saw a .45 colt round roll off a table and immediately detonating hitting the tile floor. Pretty sure it was Magtech factory ammo.

  • Verner

    I set an indoor range on fire by ejecting a cartridge that failed to fire. These things just happen sometimes.

  • John

    “They think the round fell just right and landed on a rock which set the primer off.”

    Wow, first Sigs go off when dropped and now ammo?

    What is the world coming to?!?!

  • Sledjunky

    I think a battery is to blame. I have a friend that has had that happen to loose .22 rounds in his backpack several times now and has had one go off in his front pants pocket also. And we verified that it was a battery every time. Anything else i just can’t see happening. And I am sure he doesn’t want to admit he had a battery in there with live rounds if it was that. I am sure this happens more than a person would think.