It Has to Be a Trick, Right?

The Firearms Blog has a post up about racking a Glock with just the inertia of the slide. I was skeptical, so I decided to do that math. I only have a Glock 19 at my disposal for measurement, but it can’t be that radically different than any other Glock. We can get a ballpark figure for how fast a Glock has to be moving for the slide to rack.

We can figure out how fast a Glock has to be traveling in order for the slide to rack when the Glock comes to a halt. We can do this through conservation of energy. The Glock 19 spring takes about 15 lb. or 67 Newtons to move the spring the 3.5cm it needs. Given that the energy of a spring is 1/2 Fx, that give us 0.5 * 67N * 0.035m or 1.17 Joules. To generate enough kinetic energy, the 350g Glock slide would have to move at 2.6 m/s. The human body is certainly capable of generating this kind of speed, but I’m a bit more skeptical one could stop the movement of the gun quickly enough. From a matter of force, it would take an acceleration (using F=ma) of 191 m/s^2, or about 19.5x the force of gravity. That sounds like a lot of acceleration, but it’s not beyond human capability.

What makes me skeptical is the fact that I can’t seem to reproduce this, but that doesn’t mean it can’t be done.

16 Responses to “It Has to Be a Trick, Right?”

  1. dagamore says:

    looks very cool, but i doubt it will be very practical, and yes i will try this on a glock at some time.

  2. Wolfwood says:

    There seem to be a couple people who’ve uploaded videos, so the odds are it’s real (although I’m still amazed at the things people can do with ping-pong balls in college dorm lounges…).

    It sounds like the super-quick jerk and the extra-heavy longslide are the main things; I suspect the rails are well-greased and that the spring, while “stock,” is very well broken-in.

    It seems like a purely gamer move, but more power to the guy for figuring it out.

  3. Tiderian says:

    Well, I can confirm that it doesn’t work with my Ruger P95! I tried it last night (unloaded, of course) and I couldn’t make the slide move at all. Zero.

    I guess I’m just not meant to be a YouTube superstar…

  4. Justin Buist says:

    I ran across that video about a month ago and tried it out with my Glock 21 and a snap cap.

    I can do it. Once I got the hang of it it was pretty repeatable.

  5. Sebastian says:

    Is there a trick to it? Like jamming it against the body?

  6. Justin Buist says:

    Sebastian, not much to it really. Jerk the gun backward and get it going forward nice and fast.

    Helps if the striker is pre-cocked but I was able to do it with the striker at rest too.

  7. Tam says:

    Cute trick.

    It’s helped by the fact that the G35 is lightly sprung with respect to its slide weight.

    About zero practical application, however. While not as cool-looking, snagging the rear sight is barely slower and a lot more positive.

  8. ffoem says:

    yep, seen him practice it in person. it takes a while to get it the first time, but gets easier once you get the hang of it. kind of like riding a bike. the important thing is to keep the barrel motion in a straight line and your wrist firm. i tried it with the same gun and i was close but no cigar. i don’t ahve a glock so i can’t practice it. i tried it a couple times with my sp-01 and almost threw out my shoulder, lol.

  9. jc says:

    I was there for the match. It was real.

  10. JoeG says:

    I don’t see any reason that it couldn’t be done. The human body is extremely well designed for acceleration, at nearly every joint. This isn’t all that different (mechanically speaking) than the way that sprinters leave the block.

    I would bet though that the spring in that gun has seen several thousand rounds, as they tend to get lighter the more they are shot.

    Now I’m gonna have to explain to the wife what the hell I’m doing in the garage tonight ;)

  11. HK says:

    After seeing the video, I wanted to try it with my Glock 22. I was at home, so I didn’t want to use live rounds, so I inserted an empty mag. I tried it 4 times and finally on that try, I was able to lock the slide back on the empty mag, so if it were a round, it would have chambered. I tried it a fifth time to see if I could replicate, and no go. After that, my shoulder hurt from the abrupt jerking motion.

  12. persiflage says:

    Dang! I tried that trick with my (lightly-used) Model 19, and I just could not get the slide to retract more than a half-inch. I quit trying because it started to hurt my shoulder. Other than the trick aspect, I don’t see how this is a reliable, safe and functional technique for draw/engage situations with the M19, that the operator should count on it. It would only have to be unreliable once…
    Then again, I couldn’t make it work.

  13. Brad says:

    Yep, sounds like this trick is only for Glocks with a heavier slide. You 9mm folks don’t get to play:)

  14. BadIdeaGuy says:

    That’s a cool trick- the bloopers reel of all of us trying it would be pretty hilarious.

  15. Kim du Toit says:

    Just the THOUGHT of trying this with my 1911 makes my wrist and shoulder ache…

  16. Mockum says:

    Ha! I can imagine all the middle-aged guys going to the doctor with shoulder injuries trying to replicate this. It’ll be called Glock Jerk Shoulder in the medical journals.


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