Firing a pistol underwater

Destin from Smarter Every Day captured high-speed images of both a revolver and an automatic pistol discharging underwater; the water perfectly captures and renders visible the gas forces at work in the system (and makes for a beautiful picture).

I performed an experiment to see what the differences were between semi-automatic pistols and revolvers. The advantage of shooting under water is that you can see the boundary of the gas flow fields almost perfectly.

Instead of saving for my kids' college, I make videos using the money I would have saved.

High Speed Video of Pistols Underwater - Smarter Every Day 19 (via Kottke)

(Photo: @VuurwapenBlog)



  1. Nice to have a video for those times when nerds get into arguments about whether atmospheric oxygen was required for Jayne to fire Vera in “Our Mrs. Reynolds.”

    1. Does that argument actually crop up?

      I would have thought that a quick trip to any of wikipedia’s bullet-related articles that have pictures and pointing out the quite visible lack of air holes in the cartridge would have been enough…

      1. Yes, it does crop up with surprising frequency.  The lengths people go to in an attempt to excuse the technical screwup in that episode (i.e. Jayne putting the rifle inside a spacesuit for no intelligible reason) are amazing and amusing.

        Note to Browncoats – It. Was. A. Mistake.  They screwed up.  Accept it and let it go, OK?

  2. Wow – that was cool. I noticed on the semi auto the slide didn’t lock back after shooting while it was in water like it should have.

    1. The Ruger KP95D slide lock is very firm when it’s engaged but is sometimes stubborn getting there. Usually caused by “limp-wristing” or some other form of inadequate support. They showed the “rest” that they fabricated working fine, though, so lack of support wasn’t the cause. The small lanyard could have been just enough to not let it get to the lock-back point, due to it being in an odd configuration when it was in the water tank.

      1. It’s probably best that you used a Ruger (among the most rugged if inelegant of guns) and not a Kel-Tech!

        1. There are even better choices.  Glock actually makes a “sub-aqua” variation specifically for use underwater.  And no, there’s no use looking for it on the Glock website.  Distribution is rather…limited.  :-)

    2. The slide will only lock back on an empty magazine, and it looks like they didn’t insert a magazine for these tests.

      1. The magazine’s floor plate is visible at about 2:58 before they fire. I’m not sure if the KP95D has the magazine “safety” where the magazine must be inserted in order for the action to work. I’ve never needed to shoot mine without the magazine in place.

  3. I think it was somewhat unsafe. First the block on which the gun was tested on was too small, it kicked back when the gun fired, meaning that there is no positive control over the weapon while it discharged.  Bad, very bad!

    1. That’s how a proper pistol rest is designed to work. If it didn’t move at all, something would break, and then there would be real danger. By the time the rest is going through the effects of recoil, the bullet is long gone.

      1.  Nah. What are you basing that statement on? A decent quality firearm, properly maintained, can suffer through a wide variety of indignities, including submersion. I’ve gotten MANY guns very wet, and I still have them, and they still function just fine. I *did* strip, clean and oil them when I was done, though, to prevent corrosion from retained water and the removal of lubricants.

    1. I remember that.  for once Loyd didn’t have to wrestle, he stunned them with a revolver bullet.

      In those situations, you must seal the bullet and primer with laqcer to keep out water.

      All together now “By then my lungs were aching for air!”

        1. Handgun bullets with no shoulders operate at much lower pressures than rifle bullets and would probably me much less water proof.  The crimp on a rifle bullet is pretty elaborate in comparison.

          1.  That matches up with the second book in Stephen King’s Dark Tower series, in which a number of bullets were rendered useless by getting wet. (They were hand-loaded anyway, and probably by relatively old-fashioned equipment.)

  4. That bit at the end when he was trying to say it was a toroidal blast wave and used a bagel to explain it…. Why didn’t he just say it was like blowing a smoke ring? I saw a demonstration of musket fire once where a beautiful smoke ring that lasted for over a minute and drifted for about 100 yards whilst expanding to around 10 feet across was created.

  5. It’s nice to see youtube done right: good editing, music used clearly marked in the video, access to the complete slow motion clips after the video.  Nicely done.

    And I liked the bagel.  I know what a torus is, but I thought it was a great illustration for those who don’t.

    1. He obviously had a blast (no pun intended) making this video. Perhaps causing you, dear watcher, to become Smarter Every Day is not his primary motivation, although that’s how he’s rationalizing it.

      Not that there’s anything wrong with that.

  6. If the slide didn’t function normally I’d guess it was because it had to push against water in its rearward travel, which absorbed enough energy to prevent the slide from reaching the locking point. This is a mechanically-resonant system designed to work in air, after all.

    This would be an interesting way to demonstrate/compare suppressors, assuming they can be had legally in your state, of course.

    1. Testing suppressors underwater?  You’re kidding, right?  They work by containing and slowing gas ejecta.  If you fill up the expansion chambers with water, the pressure inside the suppressor will be the same as inside the barrel.  Thin-walled suppressors aren’t built for that.

      If you’re going to test this, I strongly suggest you use one of those oil-filter adapter plate suppressors.  Then when you blow it up, you’ll only be out the cost of an oil filter.  Standard suppressors are too expensive to waste with such tests.

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