Glock 34 Slide locks back mid-stack

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  • TGR

    Active Member
    May 20, 2009
    170
    Harford County
    Glock 34 Gen 4 MOS with Vogel Trigger. Everything else is stock. 10K+ rounds thru it with never a problem. Shoot the same load of 147 plated over 3.2 Bullseye since set up. Shoots 950 fps

    Lately been getting the slide locking back at various times mid-magazine.

    The load is a very light load but has functioned perfectly in the gun since I worked it up many 1000s of rounds ago. If it was too light and stove piping or ejecting but not picking up a new round I'd understand, but it ejects the spent shell and locks back with rounds still in the magazine.

    Happens with new and old mags.

    Tried running the gun well oiled and with minimal oil as I normally do. No difference.

    Internals look good.

    Grip hasn't changed in years. Im not thumbing the slide stop lever.






    Any suggestions?
     

    inkd

    Ultimate Member
    Aug 4, 2009
    7,512
    Ridge
    If you have another slide lock assembly, try changing it out?

    Do you detail strip the gun, maybe check that the slide lock is installed correctly?

    This is all assuming that when the slide inadvertently locks back, the slide lock is what's keeping it locked back?
     

    lazarus

    Ultimate Member
    Jun 23, 2015
    13,678
    I'm guessing you have a broken spring on the slide stop lever...

    That’s my guess. Could a worn out recoil spring cause this? Is it really locking back? Or not riding forward and stripping a round?

    Could always take out the slide lock to test for a bit. It’s not critical that it is in there.
     

    GASSMAN

    Member
    Feb 14, 2009
    70
    Regardless what the issue is, with that many rounds through it I would replace every spring in the gun, including slide stop. Especially since the parts are cheap, easy to get and easy to replace. It is easy to find certified glock armorer's or attempt it yourself (if your not carrying it). I don't know where you are located but I am willing to help if need be. Also be sure you are not pushing up on the slide stop lever with your fingers.
     

    erwos

    The Hebrew Hammer
    MDS Supporter
    Mar 25, 2009
    13,866
    Rockville, MD
    Slide stop spring is either installed wrong (not under top pin) or gone out of spec. Carefully replace it. If you haven't swapped out the recoil spring, trigger spring, or the striker spring, I'd also swap those out as well... 10k is a lot of rounds.
     

    BigRick

    Hooligan #15
    Aug 7, 2012
    1,140
    Southern Maryland
    Slide stop spring is either installed wrong (not under top pin) or gone out of spec. Carefully replace it. If you haven't swapped out the recoil spring, trigger spring, or the striker spring, I'd also swap those out as well... 10k is a lot of rounds.

    This^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     

    Melnic

    Ultimate Member
    MDS Supporter
    Dec 27, 2012
    15,282
    HoCo
    Slide stop spring is either installed wrong (not under top pin) or gone out of spec. Carefully replace it. If you haven't swapped out the recoil spring, trigger spring, or the striker spring, I'd also swap those out as well... 10k is a lot of rounds.

    This is the ONLY thing I've ever had a problem with on my G17. Mine got gunk between surfaces. Pulled it apart and cleaned everything out. Worked like a charm. I could tell it was messed up cause when I pulled the slide, it was not popping back down all the way when pulling it up and letting go.

    My G17 was Police trade in, the spring was also reinstalled wrong from the beginning and had to pull it, bend spring back and then reinstall. I ordered a new one and replaced it after the above failure.

    I'm no glock expert but this may be the weakest point on that gun.
     

    TGR

    Active Member
    May 20, 2009
    170
    Harford County
    I think you guys are correct. I replaced the slide lock lever and spring probably about 5k rounds ago including the pin. I think at the time the pin was worn out of spec so I changed them both. I’ll replace them again and also do a complete spring swap.

    Let you know how it goes after.

    Happy Thanksgiving
     

    MaxVO2

    Ultimate Member
    MDS Supporter
    Slide stop spring is either installed wrong (not under top pin) or gone out of spec. Carefully replace it. If you haven't swapped out the recoil spring, trigger spring, or the striker spring, I'd also swap those out as well... 10k is a lot of rounds.

    *****This is really good advice. I have several Glocks, including competition 34's that I run a lot of rounds through and had similar problems the OP describes and replacing all of the springs cured my problem. They are cheap and easy to replace. I always have several sets of springs on hand at home and a set in my range bag in case I start having issues.

    It's cheap insurance if you shoot a lot or compete to just go through the gun every season or so and check everything out carefully. Plenty of guys who are really good shooters have lost events or done less well than they should have due to a broken spring.

    I have a G34 with easily 25k rounds through it that I've replaced a bunch of stuff on including pins, springs, ejectors, sleeves, barrel, etc.. and the thing still shoots great and accurate. I replaced more than I probably needed to do but the parts are so cheap it doesn't make any sense to me to just run it until it breaks, especially on a HD or competition gun.
     

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