Slow motion Glock Frame flexing

Slow motion of this Glock firing, shows the polymer frame flexing. I find it interesting that the take down lever moves down as the slide travels rearward.

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.

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  • Patriot Gunner

    I wonder how much this effects accuracy, if at all, because it looks like the frame starts flexing after the bullet has left the barrel.

    • JumpIf NotZero

      None. The bullet is long gone.

  • Deej S

    a reason why i dont invest in pastic fantastic….i want steel…make it last a lot longer than placstic

    • chris lynch

      Deej, if you watch slow motion firing of MOST guns, the flex a surprising amount when fired. For a real laugh, look up slow-mo AK-47’s!

    • Nicholas C

      Actually polymer flex is a good thing. Look at pressure tests done to metal vs polymer. Polymer is flexible and can rebound from certain forces. Metal is not so forgiving. It all depends on the material, and the forces acting on it.

      • dp

        You are right – polymer is ‘elastic’ but up to a point. After that it goes – plastic. Also, due to elevated heat (such as when stored in glove compartment in Arizona’s heat) it may show some creep. Although this may be ‘old news’ since plastics are improving continuously.

        • RocketScientist

          Not to be pedantic, but this behavior is true of most metals as well. Most non-brittle materials exhibit a region of elastic deformation in the stress/strain curve, then they reach their elastic limit and enter the plastic deformation region during which they deform plastically. That is, if the stress is removed, they ‘rebound’ slightly, according to the slope of their elastic deformation curve (aka Young’s Modulus), before coming to rest with some amount of permanent deformation/displacement. This behavior is not unique to thermoplastics, thermosets, polymers, etc.

          • dp

            Thanks for filling in. What we also can observe on plastics is behaviour which metals do not show and that is ‘creep’. Metals have their own specialty called ‘set’. Well they have each their own quirks.- )))
            When I see this ‘frame flex’ I do not get very excited about it; they have metal guides. Still, for common caliber carry gun, plastic is good choice.

    • Tommy Anderson

      You don’t know what you’re talking about

      • JumpIf NotZero

        He could have stopped at “plastic fantastic” and you could have made the same determination 🙂

  • JumpIf NotZero

    Having shot a glock19 under highspeed, I can 100% tell you this is flexing like that only because it’s in a ransom rest.

    I have never seen that behavior in hand.

    • Steve

      Bingo – many firearms were designed around the fact that the gun is intended to be held by a human. There are a number of semi-auto firearms that won’t even cycle if you have them in a fixed rest (or put the buttstock against a tree trunk or something).

    • dp

      What you are referring to is probably the fact that when you hold the gun in hand, the entire frame is involved as opposed to this ‘test’ when most of grip portion is isolated (from flex). It is therefore the remaining part (the rail area) which takes the brunt of the load.
      I extent you can make your guess on validity of this ‘test’.

    • 1911a145acp

      Maybe you haven’t seen it because you don’t posses Super Slo-Mo vision…..;-)


    It is interesting. And it looks to be a single pin gun (or 2 pin). Possibly an aftermarket take down lever in stainless? The source of this gif would help a little.

    • Nicholas C

      Sadly I don’t know the source. It was a non gun related page I found the animated gif.


        It is interesting nonetheless thanks! You can see why the locking block has been uprated and also a pin added. And why the old .40 frames had so much trouble in that area of the frame.

      • Nathan Tramp

        It was more than likely taken from BrassFetcher, run by John Ervin. This is definitely his style of photography (and subject matter). In fact, I think this was part of a series he did on muzzle flash. He mentioned in one of those videos that unusual flexing of the polymer pistols occured because they were mounted in a ransom rest.

  • twofistglock


  • DougE

    That’s cool. I knew the dust cover flexed a lot, but never thought about the barrel slamming down into the frame causing the middle of the frame to flex so much. Thanks for posting.

  • Gwolf

    That’s really cool. The takedown lever is a surprise.

  • C.J. Shull

    LOL @ 1:50, it jams…. perfection.

    • gunslinger

      and at :50

      • SteveA

        Not jamming they have removed the ejector.

  • strongarm

    One time ago, a similar video had been presented with a rather heavy laser pointer
    attached on the frame rails as resulting a partial take down after firing the pistol held
    on hand, with a new generation Glock.

    However, dismount lever moving is not plastic frame based. It would be happened if it
    were inside a metal frame. It depends on its inertia just after the shot realized and can
    only be prevented providing a stepped moving recess instead of current linear. During

    completing the slide reciprocal movement, take down lever spring perfectly recovers

    the situation.

    Inertial movements of tiny parts are allways rise problems on every kind of guns. Walther
    PP/PPK model pistols suffer a similar happening with sears which retain its place through
    inertia after slide slamming to the frame resulting a forward kick and giving automatic
    firing via weakened passive hammer block spring which also acts as sear director.

  • Mark Chavendish

    The flexing of the frame is a direct result of a static rest. If this
    was done with a shooter holding the firearm the energy being held in
    place by the rest would instead be transferred to the shooters hands and

    • Tommy Anderson


  • 1911-shooter

    It’s because the glock is in the vice. When you’re holding a glock, the recoil gets absorbed into your hand, not the frame. Basic phsyics, you people can stop whining. 🙂

  • DG13

    Is it me, or has the ejector been removed for this test?

  • ducky

    Talked to Glock’s chief armorer about that behavior (take down lever movement) at IWA 2007 or 2008 (don’t remember anymore) and a friend of mine same day with Gaston Glock sr. personally.
    Was visible in this video:

    They didn’t know but armorer didn’t seem to care.

  • fulcrum4257

    The frame begins to flex initially from gas expansion. You can see smoke coming from the chamber and the frame flexes outward and downward. The two or three flexing cycle of the frame begins and ends before recoil even begins to affect the Ransom rest. This is happening so fast no human would be able to see this happen in real time.

  • gala poola

    Not a Glock owner, don’t have any tupperware pistols BUT, sometimes flexing isn’t necessarily bad. Look out the window next time you fly, big metal wing flexes. Flex sometimes absorbs the shock that may have otherwise caused extra friction or wear. Maybe a steel slide on a polymer frame wears longer than a steel slide and steel/alloy combination? Not a fan of that lever moving all on its own but perhaps it’s supposed to? Nice revealing video no matter what the truth is.

  • guest

    Still beats a 1911

    Flexing… so what? Grow some muscles if the frame is “too light”

  • 1911a145acp

    Years ago after firing the first M20 I encountered, I told the owner” I can really feel the frame wiggle when I shoot it- He said”you’re imagining things” Guess NOT!

  • 1911a145acp

    The majority of the flex is in the dust cover which is really no issue at all. Steel and alloy frames flex as well -just not to the extent that the polymer makes apparent to the naked eye.. You can also see the frame flex dramatically just under and to the rear of the take down levers as the barrel cams down and unlocks out of battery. If you look at the upper most part of the frame line closely, it wiggles all the way to the rear most portion of the frame under the slide. Obviously, GLOCKs work just fine.