Tip of the day: Don’t fire a waterlogged AR-15!

This video clip is from a marketing video made by H&K comparing the 10″ barreled HK 416 with the M4 when fired full of water, immediately after being submerged.

It is a pointless comparison. Obviously Stoner did not design the AR-15 platform to be fired waterlogged. If he had it would be piston driven. Still, it is interesting to see what happens.

H/T: MP.net

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • jdun1911

    It looks like someone cut 39 second off the HK marketing video. This has been disused many time as being fake on AR15.com. There was lots of editing involved and the HK416 took longer to drain before firing.

    No rifle can safety be fire with water inside the barrel. It has nothing to do with DI or piston. It’s not my opinion its a fact.

  • jdun1911, I stripped off the marketing rubbish and “comparison” from the video because I did not think it was a fair test.

    This rifle can be fired underwater:


  • jdun

    I assumed the rifle in .ru use low velocity, high mass, small surface face(pointed) ammo, i.e something like a harpoon. In that case it would work.

    Water inside the barrel acts like concrete against high velocity ammo. I wouldn’t be surprise if the first shot out of the HK416 was subsonic in that video. Didn’t the operator manually cycle the second shot in on the HK416? I believe the operator in the video tilted his HK416 to allow better draining compare to the Colt. Tilting the rifle to drain water out of the barrel is standard procedure.

    Any rifle that has water inside the barrel will go KB. Doesn’t matter if its HK or Colt or whatever. It’s just facts.

  • Guns can be fired underwater if they are completely submerged … the water outside the barrel is just as difficult to compress as the water inside.


    If you keep both an M-4 and the HK rifles completely submerged, with just the flash-hider sticking out of the water, they can both be fired safely … they might not cycle reliably, but they can be shot.

  • HMM so when do you need to shoot a gun that was submerged???? If you are a Navy SEAL maybe, anyone else maybe once in a million years. I agree with it being a pointless demonstration.

  • jdun

    NAVY Seal doesn’t shoot their rifles submerged. Trying shooting your rifle underwater and let us know what happen.

  • Greg

    I think it’s a good thing to share a video like this. There are a lot of people out there who get their info on weapons from Hollywood action fantasies. I’ve seen a lot of dubious actions with guns on film, including firing them underwater or just as the gun breaks the surface. To show the actual results of things done like the movies might just open a few eyes & save a few guns & their owners.

  • Junkball

    The best Hollywood piece I’ve seen was No Country for Old Men where the protagonist is shown removing the magazine and clearing the barrel/chamber of his previously-submerged 1911 before shooting a charging dog.

    • Junkball, I don’t remember that. I will watch out for it next time I see the movie.

  • woodfiend

    You CAN shoot a wet AR15. All you need to do is to rack the bolt back a few times and let the water get out of the barrel. Make sure there is NO water in the barrel and you are good to go. I’ve done this before and so has my dad and brother. On the first shot, it will feel like a .22 LR because there is water in the buffer tube, but it is completely safe.

  • Anonymous

    Firing a gun underwater could very easily kill you. I read about a guy who jumped in his swimming pool to try and shoot his glock underwater and it exploded and seriously injured him. Not to mention sound travels around 4 times faster through water than air, and thus the pressure waves that will destroy your hearing and internal organs will reach you with much more force. If you do not have serious hearing protection and fire a gun underwater, you may never hear again. Kristopher claims a supersonic round can be fired while in the water but the tip of the gun in the air, I’m not sure if that is true or not, but I know for sure that you cannot fire any supersonic round with the gun completely submersed, not even a glock.

  • Joe

    hey anonymous – your wrong.

    Ever heard of a bang stick? look it up, I used to use them and my hearing is just fine.

    As far as glocks – the glock 17 model is designed to fire underwater, and I have heard of guys doing just that, even going spear fishing with them.

  • Mu

    Couple of things, first the idea of firing under water is safe because the water pressure is the same inside and out is nonsense. It is not the water pressure that’s the issue, it’s the mass/inertia. In that quoted glock example, the water in a 9mm/4″ barrel adds over six gram to the projectile that needs to be moved out of the way, your 125 grain round just became a 225 grain. Since this mass accelerates much slower, your gas pressure in the chamber exceeds specs, and your gun fails. The additional 3 psi water pressure on the outside doesn’t make a bit of a difference if you have 50,000 on the inside. You could probably make a load for a 225 gr 9mm, and the gun survives, but you run into a second issue. Even firing the gun just wet will destroy the barrel in the long run; the water forms an incompressible ring around the projectile tip which bulges the barrel when the bullet “passes” the ring.
    And didn’t they do this scene in the old “Remo Williams” movie?

  • Bobby

    Glock 22 in .40 and Glock 31 in .357 will fire underwater reliably.

    I’ve done it myself.

    LWRC M6A2 and M6A3 will also rife completely underwater reliably.

    I’ve done both of these drills myself.

    Waterlogged M6 = Working weapon. You just have to manually cycle it.

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