.44 Mag Micro Explosion In Gel Block

I am not entirely sure what is happening with this gel block test.

It is pretty standard stuff as the bullet penetrates and rips through the gel medium. You can see the temporary wound channel. However as the gel block contracts to its normal shape, there is a micro explosion inside the gel block. Which is followed by gases escaping as a form of flatulence out the entry wound. But what caused this micro explosion? Could it be unburnt gases traveling inside the wound channel? If that is the case how is there enough heat and air/fuel mixture for the detonation? Anyone have any good ideas about this phenomenon?

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


  • Giolli Joker

    Diesel effect caused by the quick compression of air and volatile gelatine vapours generated by the impact.
    We covered it on a recent article from Nathaniel on a video by The Wound Channel.

    • PK

      Layman’s terms, but correct.

    • iksnilol

      Nah, .44 mag has so much stopping power it causes explosions in the target,

    • RA

      Looks like it just adds to the pain of being shot!!!

      • jcitizen

        Body tissue doesn’t have flammable ingredients like some gel blocks do. But you are right in that when the wound channel closes, that has got to hurt even more!

        • RA

          Maybe if they had Taco Bell before they got shot lol!

    • carlcasino

      I was hoping for a new Zombie Round. The after explosion caused more damage than the complete penetration of the gel.

  • Travis

    This is very similar to what happened in the gel block with the new 5.56 ammo. The explanation that I read there was that some of the gel was vaporized because when the bullet expands it compresses the gel creating heat allowing the gel to heat up so much that it goes from a solid directly to a gas and then as the block itself returns to its original shape it compresses the gas and has compression ignition.

  • Major Tom

    Wouldn’t this effect therefore make such unsuitable for military use under the Hague Convention? It prohibits the use of explosive ammunition in small arms.

    Either that or you need to stop making flammable ballistics gel because that’s exactly how diesel ignites.

    • DIR911911 .

      maybe that’s why militaries don’t use 44 magnums

      • Anonymoose

        Maybe that’s why we should.

    • The Wound Channel

      It’s the gel burning not the ammunition exploding.

  • M.M.D.C.

    It’s called sonoluminescense. It happens in water too.


    • PK

      Various types of short-duration luminescence pop up all the time, strangely enough. The tape unrolling triboluminescence is one of my favorites.

      • Nicholas C

        Tape unrolling?

        • PK

          I tried to answer with a link to a Nature article, the comment hasn’t yet been approved but take a look:

          http://www.nature (dot) com/news/2008/081022/full/news.2008.1185.html

    • ostiariusalpha

      This is not sonoluminescence, the pressure is far too low. The is a dieseling (adiabatic compression) type of combustion of aerosolized fuel from the gel block.

      • Adiabatic compression can cause sonoluminescence. Happens quite often in clear gel, which has a high water content.

        • The Wound Channel

          Clear gel is oil based and has no water content.

          • Ballistic gel is generally a solution of gel powder in… guess what? Water.

          • The Wound Channel

            You’re evidently not familiar at all with this gel (or the phenomenon in question for that matter). Clear ballistics brand gel is synthetic, it’s not a solution of organic powder (ground up pig skin) and water.

            It’s oil based and flammable, it contains no water.

          • jamezb

            it’s also yellow and cloudy.

          • Clear gel is *not* ballistics gelatine. Period. It is not water based. It is a hydrocarbon, basically a petroleum product. It *burns*.

            In simple terms, diesel combustion is what is happening.

        • ostiariusalpha

          Water content is 100% irrelevant. Sonoluminescence is caused by the air particles shedding photons when over-energized by pressure. There is no chance in heck you are going to get that from clear ballistics gel, it just doesn’t have the required mass to collapse with enough force.

        • The material safety data sheet for Clear Ballistics gel clearly indicates that it is 75-95% oil.


    • Nicholas C

      Yeah I dont think that is what is happening here. The explosion in the .44 mag gel block looks like combustion rather than light.

      • The Wound Channel

        Correct Nicholas, this is combustion just like a fire piston.

    • RocketScientist

      It is not sonoluminescence. Sonoluminescence requires very high frequency vibration/shock waves, bubbles on the size scale of 1 um (0.001 mm), and the flashes occur on a time scale in the dozens of ps (picoseconds, or 0.000000000001 seconds).

    • Hensley Beuron Garlington

      I knew I’d seen this covered and forgot by who. Thanks for posting.

  • Adiabatic compression sonoluminescense. Happens quite often in clear gel blocks, due to their consistence. Using the more dense FBI-grade gel blocks gets rid of the problem.

    • PK

      Extremely sciency, but correct.

      • Giolli Joker

        It seems more of a combustion, with resulting fumes, than sonoluminescence in this case.

        • Adiabatic compression *is* basically the stroke that happens in diesel engines. But here you have nothing like a combustion, what you see is actually a vaporized gel. Clear gel
          has a high water content. The high velocity passage of the bullet
          creates compression, which creates heat, which heats up the gel up to
          vaporization point. When the block returns to its original shape after
          the bullet exits, the gel is expelled violently through the cavity.

          • Giolli Joker

            Clear ballistic gel according to the manufacturer :
            “The flash point of our ballistic gelatin is 325 F /162.77 C.”
            While sonoluminescence is possible, it can happen in pure water and it doesn’t ignite anything, this still looks to me flammable vapour taken above flash point by sudden compression.

          • ostiariusalpha

            You are correct; Pier, on the other hand, is talking nonsense.

          • I still stand my opinion. Let’s give it a try in a lab, shall we?

          • Giolli Joker

            Pierangelo, è un fatto che la gelatina trasparente non abbia acqua e sia infiammabile, con una temperatura di accensione relativamente bassa. Se sostieni che la causa sia il contenuto d’acqua, parti da una supposizione sbagliata e il test in laboratorio è superfluo.
            Se poi esistono altre composizioni di gelatina balistica con acqua se ne può parlare, ma questa è quasi sicuramente Clear Ballistics, ed ha le suddette caratteristiche.

            In English, briefly:
            Clear Ballistics gelatine has no water and has a low flash point, if the assumption for sonoluminescence is water content, there is no need for a lab test, as the the assumption is wrong.

            Nevertheless, we would all enjoy more videos of gelatine blocks being shot. 🙂

          • CountryBoy

            Still wrong.

            This is clearly combustion, not compression sonoluminescense.

            There is no water in the gel; it is oil-based, and when mixed with air and compressed, is flammable in the same way a diesel engine’s fuel/air charge can be ignited by the compression of the piston.

            The resulting exhaust is the “flatulence” seen on the left as smoke.

    • Drew Coleman

      I know some of those words.

      • billyoblivion

        Compression, and then most of them following “Happens”.

    • RocketScientist

      Its not sonoluminescense. Sonoluminescence is a very specific subset of a related behavior. It requires very high frequency vibration/shock waves, bubbles on the size scale of 1 um (0.001 mm), and the flashes occur on a time scale in the dozens of ps (picoseconds, or 0.000000000001 seconds).

      What IS happening is approximately adiabatic compression as youve noted. However the flash is from combustion processes (vaporized ballistics gel+heat+compression) not sonoluminescense.

      • THIS reply is way more polite than your other. And, I tend to consider your explaination just as good as mine rather than telling you that you “flat out don’t know” what you’re talking about.

        Sounds like something that would make up for a very good aimed experiment (read: a great excuse to shoot lots and lots of rounds into gel blocks).

        • jamezb

          am I the only one that sees the burned BURNED – AS IN SHOWING VISIBLE MARKS INDICATING COMBUSTION – gel in the wound channel after the flash?

          • jamezb

            …because I could be going blind, and if so I need to know.

  • The Wound Channel

    I’ve demonstrated and explained this several times on my channel. Clear gel is flammable and when the TSC collapses it acts like a Fire Piston and combusts.

    • I beg to differ. It is an adiabatic compression sonoluminescence phenomenon. There
      is no combustion, what you see is actually a vaporized gel. Clear gel
      has a high water content. The high velocity passage of the bullet
      creates compression, which creates heat, which heats up the gel up to
      vaporization point. When the block returns to its original shape after
      the bullet exits, the gel is expelled violently through the cavity.

      • The Wound Channel

        Sonoluminescense is the emission of light, not fire. If you watch the videos on my channel you can clearly see it is combustion, with exhaust gas. The combustion happens after the TSC collapses and creates pressure high enough to ignite the gel/air. Just like a fire piston. The bullet is long gone before any fire happens.

        Clear gel is oil based and has zero water content, you have to be careful when remelting after washing that you don’t get any water in the gel as it will pop/crackle during the melting process.

      • RocketScientist

        You flat out dont know what you’re talking about. Despite your (incorrect) usage of large words. Sonoluminescence requires very high frequency vibration/shock waves, bubbles on the size scale of 1 um (0.001 mm), and the flashes occur on a time scale in the dozens of ps (picoseconds, or 0.000000000001 seconds).

        • The tone of your post would deserve an F-U as a reply, but I’m too polite for that. I stand my opinion. Let’s resolve this the proper way: with a lab experiment.

          • RocketScientist

            We don’t need to run an experiment. It is demonstrably NOT sonoluminescence for a wide variety of reasons. The FACT (not opinion) is that the frame rate of the camera used to film this would be way to slow to even capture flashes caused by sonoluminescence. The fact that we’re seeing anything in this footage confirms that whatever we ARE seeing, its not sonoluminescence. Further sonoluminsecence only works in ambient phases of high concentrations of noble gas and water vapor. In practice, this is accomplished by depletion of nitrogen and oxygen through chemical reactions over the course of hundreds of expand/collapse cycles. Here we have one cycle, during which the entire cavity is open to ambient air (with its extremely low concentration of noble gasses). Also, again there are the time scales and size scales I’ve mentioned, not just of the flashes, but of the in put compression/shock. It requires much higher frequencies than we are seeing here. I have no idea what the frame-rate of the camera used was, but lets be EXTREMELY generous and assume that bullet traversed the entire gel block at its muzzle velocity, and the gel block is 2 feet long. This would give the frequency of that bubbles axpansion/collapse cycle a frequency of something like 500 Hz, far below that neccesary to create sonoluminescence in water, much less the EXTREMELY more viscous ballistics gel.

            And I’m sorry if mean words hurt your feewings. If you’ll notice, my replies started off very matter-of-fact. I got a little testy (and still, never made it personal, just said you were wrong and didn’t know what you’re talking about, which is patently true) only when you started arguing with people, using words you obviously have a limited understanding of, and when your arguments consisted of essentially repeating your previous, incorrect arguments. I don’t know you from anyone, have no opinion as to anything about you or life, other than that in this case, you are factually incorrect. If me saying as much leads you to want to threaten me with copulation, then that’s on you. Seems an overreaction to me, but hey, what do i know. Have a great day.

          • I’d appreciate to know where did I sound butthurt to you or where exactly I threatened you. Whatever. I can live on.

          • RocketScientist

            “The tone of your post would deserve an F-U as a reply”

            Hmmm, wonder where I got that idea…

          • Yeah, well. The tone of your post *objectively* deserved an F-U.

            But I didn’t sound butthurt one little bit, and didn’t threaten you. Just pointed out a fact.

            Because, you know, Mr. “I’m sorry if mean words hurt your feewings”, when you have strong arguments (which by no means I doubt you have), you don’t need to use “mean words”; they will just make you sound ineducated and not help you to get your point across.

            You need to learn a few lessons on divulgation, my friend. Using the language you want is a great American right, but then, don’t expect people to just fall in line with what you say.

            Nighty night!

          • RocketScientist

            Hahahah! At this point I have to assume you’re trolling me. The more you protest about how not butthurt you are, the more evidence you provide confirming that you, in fact, are. And all your talk about mean words… I only ever said you were wrong. Youre the one who told me to go f*** myself (ie, threatened me with copulation). Lastly, you might want to go back to whatever thesaurus you looked up “divulgation” in. It doesn’t really work in this context. It pretty much only ever is used with connotations of publishing or spreading publicly (one could even say divulging) information that was previously only know to yourself or your group.

          • The Wound Channel

            Owned lol

          • RA

            Can’t we all just get along.

          • RA

            Hey you’re a smart guy and a gun enthusiast so we are all on the same team. We already have enough anti gun enemies to deal with. United we Stand divided we Fall. I do agree with your conclusion as well.

          • RA

            Hey you’re a smart guy and a gun enthusiast so we are all on the same team. We already have enough anti gun enemies to deal with. United we Stand divided we Fall.

          • M Darwin

            That’s buttwound’s, (wound channel) standard reply when someone disagrees with it! Don’t pay any attention!

          • R H

            Definitely don’t need a lab experiment. It’s combustion. Not sure why the sonoluminescence myth took off like it did, but the flash fits almost none of the criteria for sonoluminescence. Nothing wrong with being ignorant. Obviously people who’s careers revolve around firearms don’t know what it is, and TONS of people believe as you did.

          • Beard!
          • randomswede

            As a side note, not directly related to this discussion:

            Is there really nothing wrong with being ignorant?

            The “true” use of the word just means a lack of knowledge, but as it’s commonly used it means holding and usually spreading erroneous information.
            We humans aren’t equipped to challenge every piece of information we encounter, we’d do nothing else, but if we spread false information as true to people who trust us, down the line that’s probably not going to lead to good things. So whilst it’s understandable and human I’m not sure it isn’t wrong.

            Then there’s willful ignorance where the majority of the evidence or all actual evidence points to something but the person chooses to cling to little or no evidence, usually for emotional reasons or pride. That I would hope most people see as wrong, even though I’m sure any adult harbor some to protect themselves.

          • The issue is not about being being ignorange. The issue is: when people is
            right (and after double-checking I realize they were right and I was
            dead wrong!) but can’t express their truth in a polite way, that
            undermines their point outright.

          • Being debunked politely is nice and I accept it. Being debunked rudely isn’t.

          • RA

            You still shared your perspective so that’s worth something. Don’t sweat being wrong even ehrn people are blunt. You’re still a valuable part of the gun group and that matters in my book. Tomorrow is another day we all can share and talk about what we love about firearms, shooting, and support each other in that.

          • The issue is not about being being blunt. The issue is: when people is right (and after double-checking I realize they were right and I was dead wrong!) but can’t express their truth in a polite way, that undermines their point outright.

          • Archie Montgomery

            A demonstrable, repeatable experiment? Sounds reasonable to me.

        • BR549

          Pierangelo brings up an interesting possibility with it being a compression sonoluminescence phenomenon, but first off, I disagree with it being adiabatic since his hypothesis requires heat transfer in order for the gel vaporization to occur.

          Also, it appears that in order for the light emissions to occur ENOUGH to be observable/recordable, certain stability conditions would have to be maintained, and that was not considered a part of the ballistics experiment. Also, the emission appears to require a temperature of 35,000F. After looking into the issue, it seems a bit unclear whether that 35,500F is necessary for a simple, one-off, expression of the phenomenon, or is that temperature one of the conditions of stability to allow for a continuous emission?

          While I tend to side with you in your assessment, I really think you need to work on your bedside manor. Perhaps cutting back on the caffeine might help. :o)

          • ostiariusalpha

            If you can maintain the pressure in the air cavity, such that the temperature is constantly at 35,500°F, then light transmission will be continous as long as you like. Neon signs use electric charge to supply the energy to a gas, instead of pressure, but the basic principles are the same.

  • Bruce Fleming

    Once again TFB brings “news” to us that has been discussed for a couple of years on the Internet.

  • Bill

    Flatulance? You mean that happens when I fart?

    • Nathan Alred

      So those are smoke stains back there?

  • FLdeepdiver

    I see this all the time in clear synthetic gel. Adiabatic compression occurs and the makeup of the gel facilitates ignition. Nothing monumental here…

  • cosmoline_covered_Ferret

    Starting to wonder is Nicholas C is capable of coming up with anything new. Ripping youtube videos and regurgitating information that is old news is not writing.

    • Ben Warren

      Old news? I saw the video yesterday for the first time. Not all of us are up to date on everything that goes down on youtube.

  • Will

    It’s commonly known as the PFM effect.

  • schizuki

    I’m not saying it’s aliens. But it’s aliens.

  • Sickshooter0

    It’s obviously a 44Mag shape charge modeled after the Panzerfaust. I could be more highly sciency, but I had pasta for lunch and I am too sleepy.

  • Dinkum_Thinkum

    Not only does the .44 mag “go through an engine block”, it turns stuff INTO an engine block and THEN goes through it.

    .44 mag, the Chuck Norris of handgun cartridges.


  • John

    This is known as bactoluminescence.

    It is all the bacteria in the gel simultaneously holding up their lighters at the awesomeness of the .44 magnum!

  • Edeco

    Watching the Taofledermaus test tube torcher tests I was often surprised how fuels could vaporize without burning or blowing up. I mean, I know why in theory, but cone on, with a torch right there?

    Point being the gel thing is like the opposite; stuff getting surprisingly explodey with compression.

    • Swarf

      I’d like you to know that this comment was the wrecking ball to the rest of this thread’s nerdy science Ivory Tower cred.

      Congratulations. You broke it.

      • Edeco

        Woot 😀

  • Sasquatch

    Amazing what the air we breathe does under pressure.

    • R H

      Amazing what the air we breathe does when pressurized, mixed with fuel, and ignited…

  • Tim

    Two missing pieces of data- how far is the muzzle from the gel face, and is this truly oil based clear gel?

    The first issue is only to address your question of unburned gases, especially considering the fireball from the muzzle. There’s no evidence of combustion or heat while the bullet passes thru the gel, just the typical oversized channel expansion (ref Lucky Gunner ammo tests). I doubt it’s unburned gases, and I see no fire near the gel face, but the distance would be nice to know.

    So when the channel suddenly expands, it creates a huge vacuum in the cavity which undoubtedly causes some oil in the gel to vaporize. When the cavity collapses, this hopefully flammable vapor and any air that came in with the bullet mix, compress and get hot. At that point, it either spontaneously combusts, i.e. diesels, or is helped by hot muzzle gases or hot powder residue that followed the bullet in or even shards of hot bullet to ignite the oil vapor-air mix. This is actually pretty obvious in your picture of the ignition which shows a lump from the combustion on the top of the gel block. Lastly, when this lump collapses, it farts out the gel oil exhaust and possibly unburned gel oil mist. More evidence of gel oil burning. qed

    What I’d like to know is whether this was a one time occurance and if not, whether it happens with other calibers and muzzle distances?
    Flammable oil based ballistic gel, what will they think of next…

  • Giolli Joker

    Yes, same basic concept.

  • Being debunked in a polite way is always nice.

  • Old Vet

    Not a scientist here, but all the big words below impress me……cool video though.

  • JJ

    Dieseling is fun in airguns. Adds a bit of oomph. This looks like some powder on the tail end of the bullet dropped off in the gel and ignited. Maybe someone used alcohol to mix up the gelatin. Regardless, that is quite a pop and makes the gelatin jump a lot.

  • Mark H

    I think it’s gun powder from a hollow base bullet. HSM brand in 9mm and 45acp.

  • Mike Lashewitz

    What I am seeing is a friction caused chemical change making the jel react like a diesel explosion.

  • Archie Montgomery

    Donning my costume as Captain Obvious, allow me to point out this seems to be a rare event. I cannot remember a prior announcement of such an event; being in my middle 60s and having been actively shooting and following such matters, that is telling.

    Speculation: I’ll defer. Has the author ‘smelled’ the gases from the gelatin block or had them analyzed? I know of nothing in either gelatin blocks or lead and copper jacketed bullets which either burn or explode – normally. Could it be some impurity in the gelatin?

    At one point, some many winters ago – in the late 1970s or very early 1980s – I bought some “S&W-Fiocchi” ammunition in .38 Special +p with lightweight bullets. The jackets were silver colored and I believe they were aluminum. When fired onto a metal plate target, they would ‘fireball’ in a similar manner; a quick bright red to dull yellow flash of light.

    I presumed the aluminum in the jacket was fragmenting sufficiently to burn under the instant heat and pressure. Just for the record, I didn’t hire any chemists to test that hypothesis.

    If one could make this happen on a predictable and reliable basis, one would probably be outlawed by the Hague agreements and vilified as a witch by the hoplophobic faction.

  • markrb

    Who cares….it makes me want to get a .44 mag!

  • Starfire

    Chuck Norris made the shot, enough said!