Episode 34: Bulletproof Water

Air Date: July 13, 2005

Hiding underwater can stop bullets from hitting you.

partly confirmed

All supersonic bullets (up to .50-caliber) disintegrated in less than 3 feet (90 cm) of water, but slower velocity bullets, like pistol rounds, need up to 8 feet (2.4 metres) of water to slow to non-lethal speeds. Shotgun slugs require even more depth (the exact depth couldn’t be determined because their one test broke the rig). However, as most water-bound shots are fired from an angle, less actual depth is needed to create the necessary separation.

It is possible to do a chain-straight 360° loop on a swingset.


Under one’s own power it is impossible to do a chain-straight 360° loop on a school yard swingset. With help of other pushers, it is possible, although highly difficult, to do a full circle without the chain being straight. A person would need a rocket strapped to himself to do it. A dummy was set up in such a manner; the rocket was able to propel it in a chain-straight 360° loop, but the setup would be too dangerous with a real person.

It is possible to do a 360° loop on a rigid-arm swingset.


A seventh generation circus performer confirmed the myth by doing a 360° loop while Tory, Kari and Grant observed. The others were not able to do the loop, as it consumes a lot of energy.


  1. Ray says:

    Thank goodness for that!!! I had been trying that as a kid, only to get a bumpy chain. Heres one. When I was about 5, curiosity made me look under the merry-go-round as it was spinning around. Yep, there was a shallow bit, and I had my head painfully stuck underneath it with my mum pulling me out. All in the interests of science. I wonder if the myth about me having no brain can be busted???

    • vernick says:

      you only tried on that one set and can you say you tried every single swing set? trust me, this can be done, I have done it as a small child, the thing is it can never be done if there is much distance between you and the top bar, there must be a very short distance between you and the top bar and this all happens very quickly with momentum. mb used large adults and dummies to perfom 360, thats not going to do it and its not the same as a lot of kids doing it growing up that I know

      • Peter says:

        You can with a solid type swing when the side bars mount is fitted over the swing frame so the swind is able to go right over .You face the swing rear and hook your toe under the seat bar (basket) we used to do it as children standing of course.

  2. James says:

    Was there ever a comparison to arrow/crossbow penetration in water?

    • judy says:

      I need someone to send to me this data about YES you can go over a swing bar..I know there was a kid in my school done this.,.as did a son and grandson..they had no weights and done it. Now I need others to write and tell me trhey done this too.

  3. Ken Biswanger says:

    Firing a bullet at the water at the wrong agle and it would break up or bounce off. Ever slap the surface of a pool with your bare hand? I wonder though, if you were to fire a gun while it was completly submerged IN the water and the barrel flooded with water, if the bullet would go futher than 3-8 feet. There would be no impact of the bullet and the water to slow it down. Though the friction of the water would certainly slow it down. And what about shooting a bullet from under the water at a target out of it?

    • bob says:

      wow that is dumb. if there is any obstruction in a barrel it will rupture due to pressure.

      • Adrian says:

        So this means if you shoot a gun underwater at your foot it won’t go thought your foot.

  4. Lill Nilsson says:


    - I was a bit disappointed when you busted this myth, because it´s not a myth.
    I have actually done this several times in my childhood. And so has many of my friends back then.
    The difference lies in the swing. We had rubbertires as seats, fastened with stiff ironbars to the chains holding it. The swing hung from a long log in a timberrack. The friction in therack might just be the helping hand in my case, but I think you should revisit this one.. We had no rockets helping us.
    Despite small details like this one; we sincerely love your show!

  5. Piret says:

    About the 360.. Don`t know about the swing with chains. But here in Estonia, there are swings built to do a 360. No circus needed :) Check it out: http://www.kiiking.ee/?id=75

  6. Ballard says:

    …should have tested ‘armor-piercing’ bullets into water (…especially .50 caliber). These bullets are primarily steel, and much less likely to shatter on impact.

    Only lead bullets were used on Mythbusters.
    Lead is obviously a soft metal, much more likely to break up when impacting water or hard sufraces.

  7. Mike b says:

    Firng a weapon underwater with the barrel full of water will do one of two things, split the barrel or the chamber. It would not result in improved penetration of the water, just maybe the firer. As far as i know this is the only firearm that can be safely fired underwater and the projectile is actually touching what you are shooting at in the first place. http://en.wikipedia.org/wiki/Bangstick

    Many spearfisher men in teh early 60′s and 70′s in Australia carried one of these usually using either a .303 FMJ or 12 shotgun cartrige. Deadly against sharks.

  8. Kevin says:

    There are a couple of factors that were left out in the discussion of whether a swing can do a 360. The most important one is the LENGTH of the swing. If you look at the physics (and math) for having a chain-based swing do a 360, it needs to be taught at the top, with an centripetal force equal to gravity (mg = mv^2/r), or Energy E=1/2 mv^2 = 1/2 (mgr). The difference in potential energy from the top to bottom is mgh or 2mgr. so the total energy at the bottom to make a full loop is 5/2 mgr = 1/2 mv^2, or v = sqrt(5gr). The shorter the chain, the easier it is to make it do a 360.

    I have personally made an empty toddler swing (about 5 feet long) do a 360. The method used by the MythBusters was less than optimal though – rockets apply a lot of force, but don’t transfer much MOMENTUM. What’s needed is a rapid transfer of momentum to the swing (like pulling it way up and throwing it down hard – called “impetus”.

    I’ll have to give it a try with my 5-year-old next… ;-)

    • Eric says:

      i totally agree, this is in fact possible and really no rocket science, i did it with my friemnds growing up when i was like either 6 or 8 years old, the trick was being light, rolling up swing seat to shorten chain lenth and with just a few swings back and fourth sure eno8ugh we made it over, mind you this was only done once at a time, mythbusters need to do this over. i pissed because i can’t prove this no longer as an adult weighing 260 pounds, grrrrr

      • Eric says:

        sorry for typo’s i forgot to mention that you also have to do standing up , with knees slightly bent, can some one please post something with proof as im being told im making this up when in fact im not

      • john says:

        there really was no way for mb to really perform this the right way because they can’t force a child which is what is needed to perform this action,small dummie produces no energy and full grown adult weights way over 40 pounds or so however a full grown adult miget would work with short chain lenth

  9. Frank says:

    I think the phrase that describes the result of firing a gun underwater is “breech velocity exceeds muzzle velocity.”

  10. Frank says:

    Oops – just read on Episode 51 that a gun can be fired underwater. Learn something new every day…

  11. Gary says:

    I saw a guy fire a .22 pistol completly underwater, doing something highly illegal, (shooting trout). It stunned them to the point he just picked them up.

  12. chris says:

    did u try fmj s on tha water myth? iv found that the best way to shoot sumthing under water is with a 22 using sub sonic solid nose/fmjs

  13. Josh says:

    I am a big time hunter i do it every week end and have killed many deer. there is no way those were solid metal jackets you were shoting i actually went out and tried it and it worked with my 243. wen i first bought them i shot a deer but the bullet just went straight through causin minamal damage. A bullet that mushrooms peels back like a orange from the tip if shot a close ranges there is to much energy causin the bullet to peel all the way down leaving strips of metal just like you had

    Definatly a re-visit

    • Jonah says:

      I didn’t know deer lived underwater. Metal jackets or not, the experiment had nothing to do with the aftermath of rounds penetrating deer, “big time hunter”.

      • sky says:

        I was just thinking the same thing like weren’t we talking about firing under water lol

  14. Will Wallaby says:

    James asks:

    “Was there ever a comparison to arrow/crossbow penetration in water?”

    The range ought to be somewhat less than a speargun, because the spear has a comparable cross-sectional area ( drag ), but nore mass and therefore more momentum. The rate of slowdown is proportional to projectile drag duvided by mass,

    Speargun spears are designed differently from crossbow bolts — spears have narrower, more streamlined tips to cut through the water. Crossbow bolts typically have wider tips to do more cutting damage on impact — the problem being that if you fire a stubby, wide-tipped projectile into water, there’s too much drag on the front end, which tries to decelerate faster than the back end, and the projectile tumbles end over end, slowing down when it’s broadside to the water. Crossbow bolts have no spin stabilization to keep them going straight ( nor do speargun spears, but they travel at most a few spear lengths ).

    Early shock-hunters and whale-hunters did at one time use beefed up bow-mounted crossbows with a line attached, but these were superceded by gas-powered spearguns. The target whale or shark was always either on the surface or very close to the surface, in very close proximity to the chase boat.

    You probably wouldn’t want to fire a modern hunting bow or crossbow from underwater, because the bowstring would be impeded by the water, slowing it down and throwing your aim off. That’s why elastic-powered spearguns keep the elastic band edge-on to the direction of motion, to minimize drag.

    Firing a crossbow down into the water woult likely have mixed results, depending on whether the flat of the arrowhead slapped the water like a skipping stone.

    The main question I’m guessing would be how crossbow-fishing or speargun fishing qualifies as a myth. Obviously you can spear a target underwater without letting go of the spear. Obviously you can shoot fish from a boat with a crossbow, as Burt Reynolds was shown doing in the movie Deliverence. The only question is effective range. You won’t get much more range by speeding up the projectile, because water is nearly incompressible — plowing into water at high speed is like hitting concrete, so a carbon-fiber crossbow bolt will simply bend and deflect. A crossbow bolt isn’t going to be much geacuer than the .50 cal. round that disintegrated on striking water. A tungsten elephant-gun round wouldn’t have traveled much farther without slowing down — the general rule is that a projectile koses most of its muzzle energy after oushing aside a total mass of water equal to its own mass, which generally happens after 10-15 projectile-lengths, whixh for a crossbow would be the heavy metal tip on the bolt, not the lightweight shaft which is only there to stabilize and facilitate launching and extraction.

    If you were to take the heaviest crossbow-bolt tip you could find, and accelerate it to elephant-gun-round velocity ( the two rounds having roughly the same mass ), the recoil would would be equally wicked. Elephant guns are large and heavy for a reason — to help absorb the recoil.

    Another fact not mentioned is that if a super-spy were to fire a Dirty Harry type magnum from underweater (a) the recoil would be much greater assuming the gun didn’t burst, and (2) the stunned super-spy would float to the surface along with stunned trout, probably bleeding from the eardrums and eyeballs. When a heavy-caliber round broke open the large and heavy Mythbusters tank, imagine what the concussive damage would have been to a person IN the tank.

    Still, the question of crossbows DOES have special effects appeal — we’d get to watch Janmie stumping around on a wooden leg in Captain Bligh regalia in heavy spray. Aye matey, but it’s bad luck to have a woman on board unless she be ships’ blacksmith — and what DID early whalers use for lightweight line that could hold a whale ?

  15. Ken Hyland says:

    Hi,I liked that show,but seen some things that would effect results. First of all you are right shooting straight down into water increased the bullets effectiveness.
    Except the high powered rifles,that’s because the bullets aren’t designed for impact at point blank range.So a slower rifle round would be better.Best rifle rounds would be solids made for elephants and dangerous game.Like big solid 500 grain
    45,50,cal and up nitro express rounds. Like you said 9mm can go up to 8ft down so that would be over the dept of a regular pool.Also guns like the 1911 .45 can be shot effectively.But barrel must be tiltedup before firing to remove a air bubble.Use waterproof ammo that like miltart varnishes primer and aroung bullet/casing meeting point.Danger one word of caution,fire guns remotely,with a rope or any design you choose.Because the guns can explode!!!!!!!!!!!!!!! Great show thanks!!!!!!!!!!!!

  16. Ken Hyland says:

    i forget to add the 1911 can be shot underwateri

  17. Mr Man says:

    For maximum penetration of high velocity projectiles into water use cavitation projectiles.FMJ rounds go further into water than sporting projectiles.Hand guns(note that – handguns) can be fired underwater – I’ve seen it done(also from underwater to an air target).There are a couple of underwater fire arms – HK make one (electricity fired pistol)-Soviets have two,an AK47 derivative and a pistol.
    Don’t believe everything on TV.

  18. Christopher Treptow says:

    Good gun myth,but wouldn’t the shock wave from the bullet hitting the water kill the shootie.

  19. jason says:

    A glock is designed to be fired underwater. Glock sells a spring cup to protect the firing pin.

  20. Ben L. says:

    We are in the Middle East at an undisclosed air base and watch your show everyday at noon. Today we watched the episode above and might add you need to try using only solid, hardened, lead bullets with no copper jacket that starts the frag process.
    Try it and we will be watching. I think you will find better results.

    “Takin it to THEM before THEY bring it to US AGAIN!!!!

    Keep em coming guys we love it,

    • Danny says:

      My brother was previous military and refuses to believe this result I would really like a re-visit on the issue with the different bullet types listed here

  21. Therese says:

    It is possible to do a chain-straight 360° loop on a swingset!! I did it when I was little on my backyard (standard) swingset. I shortened the chain until my head was very close to the cross bar. I did a 360° once, and I thought it was so awesome I had to try it again. The second time, I got to the top and fell straight down, nearly hitting the bar. Needless to say, I never tried it again. But, the myth should definitely not be busted!

  22. Ted says:

    Glock 19 (and others) will shoot under water. Check out the youtube video. That is one of the reasons they are the best handguns made.

  23. Bill says:

    Falling from a great height over water usually is fatal, but if someone had a “surface penetrating cone” under one’s feet, could one survive?

  24. Ryan says:

    hey can anyone plz tell me which is the most gun that penetrates water and how much depth did it get ?? and what was the M16′s depth ??

  25. Steve T says:

    you can shoot bullets into water and have them go 20 feet at a 30 degree angle if the water is broken up… by meaning broken up is like diving into a swimming pool from any height… they spray water into the pool to keep from breaking the divers wrist… so if you shoot any bullet in water that has ripples or waves you can get penatration without discinagration!!! sorry Adam and Jamie… it is plausable

    • Jon Hallin says:

      In diving competitions they spray water onto the surface so that the diver will be able to see the surface, something that can be very tricky if it’s completely calm.

  26. 123456789 says:

    the swing thing was busted but ive done it before…..

  27. lance says:

    to do a 360 loop with a chain link swing is possible. the team went about it the wrong way, the seat has to be a solid, not that rubber strap the team used. plus you have to do it from a standing position. which will help you get the centrifical force to keep the chain straight.

  28. moon says:

    in ref. to underwater escape, i noticed u had some plastic rap or celefane stretched in front of the gun,dont u know, when a bullet hits something, anything, it will start to come apart,no matter what the object, or kind of bullet. naturally,more velocity,worse fragmentation. so how can you tell if it would be lethal, if its already separating when it hits the water?

  29. Kavall says:

    Bullet’s do not come apart if it hits something. Not all bullets are considered equal. Hollow points are designed to expand, as they expand they typically break up, to a degree, which is why they have measured weight retention in bullet ads. Full Metal Jacket ammunition does not expand and does not break up till it starts to tumble. If the bullet continues straight it won’t break up. Armor penetrating ammunition is often a steel or tungsten core wrapped in lead covered in a copper jacket. That’s a lot of materials that can break up if they tumble. The most interesting thing to test would be a dangerous game bullet of solid copper or bronze. That’s just one solid chunk of metal that would be far less likely to fragment, period.

    On guns shooting under water. All guns will shoot under water. It’s the ammunition that poses the greatest problem with them firing under water. Early flintlock guns will not shoot because the primers are a pan of black powder and it gets wet. Wet powder doesn’t burn. Modern metallic cartridges are pretty well sealed and WILL fire underwater. Julian Hatcher, a retired U.S. Army major general, proved all this through extensive testing WAY back in the early 1930′s. There have even been guns made specifically to shoot underwater (mainly just projectiles more suited for underwater “flight”) Heckler and Koch P11.

  30. real world says:

    sorry, but this is BS. a full metal jacket will NOT expand,explode, or disintegrate when fired into water(flat surface or otherwise). the projectile will remain intact. hollywood is hollywood and the rest of the world is the real world. this episode was all the rave at work until i fired several different caliber rounds into water at several different angles and all remained intact. perhaps the owner of the pool you were shooting into would not allow the a real test and hollywood once again made a myth of its own. which makes me leary of many test you have done

    • sky says:

      You shot into the water the article is about shooting from under the water

  31. real world says:

    on pistol bullets, hollow point ammuntion can be fired into a average garbage can(39 gallon) full of water and wont hit the bottom. .380 to .45 acp average depth is about 3 feet. fmj ammunition would provide a deeper penetration. also most pistol ammunition are also supersonic

  32. Kristin says:

    the 360 swing thing should not have been busted ive done it half a dozen times on a swing set down the road from my house its a normal chain link rubber seat swing set, and oh wait let me check…nope no rockets strapped to my butt

  33. Glen says:

    Just an Idea. When you fired the big bore rifles at the pool you were up close (point blank). when you fire a bullet its velocity reduces with distance , and the projectiles mass stays the same. So there must be a moment where ( in the case of the .50 cal ) the velocity is reduced to a point where the projectile will stay intact and will travel further through the water because of its larger mass . this could be tested by lowering the charge in the bullets,to recuce the velocity and still fireing them into the pool at point blank range. (This will reduce the risk of missing the pool from a mile away :-))

  34. Glenn Rosenthal says:

    Jamie, Adam, I am very entertained by all that you do and I am sure that not only do you take the proper safety precautions, but I am also sure that you do all of your experiments with the founding principle that science is important; Sometimes dangerous, always contentious, but in the end I don’t think you would prevaricate or B.S. me for the sake of television ratings. I truly think the both of you do your damdest to find results without compromise. Anyway; people are entitled to their opinions. I loved Lead Balloon and Seesaw Slingshot very much.

  35. A nu B says:

    The issue of a super sonic bullet being stopped by water can be explained by simple fluid mechanics. First fluid can not travel faster than then the speed of sound. In air, a bullet creates a pressure field around it (the air compresses until the bullet passes and then it expands back). Secondly, water is generally incompressible; therefore, a large amount of energy is required by the bullet when it enters the water, generating a large amount of heat and melting the bullet. This is the reason subsonic bullets travel further in water.

  36. Uhm, guys? says:

    Seriously? All these people who “totally did a swing set 360″ or “bullets don’t work that way in real life” etc. Mythbusters tested it and put it on video. That trumps a shitty internet post. If you want to say they’re wrong, post a video of your own on Youtube or whatever and link to it. If you don’t do that, it’s just a lot of empty BS.

    Some choice gems:

    “Bullet’s do not come apart if it hits something.”
    -Besides the grammatical errors, which we should charitably ignore since this IS the Internet, bullets simply do come apart if they hit something. You don’t have to be a gun nut, or even a wanna-be poser, to know that. You just have to have a bit of sense in your head.

    “I have personally made an empty toddler swing (about 5 feet long) do a 360.”
    -Great job, now try sitting in it and doing that. One time I personally made a yo-yo do a 360 but that has just as much bearing on this as your experience.

  37. johnny says:

    when firing in to water what would happen if u used oil eg engine oil would it slow quicker again?

  38. J says:

    All I want to know is why they didn’t do a Super slow-mo of Tory’s chain break on the swing. Dissapointed

  39. everthewatcher says:

    The BBC’s Bang Goes Theory did a the 360 degree rotation on a chain swing carrying a person in 2011.

  40. forsaken says:

    on bulletproof water no one even thought of trying a .22 caliber bulet. it should definetly be a re-visit

  41. Adrian says:

    if you shoot a gun underwater will it go through your foot.

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