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Doubling (tripling and so on) of fire on Glock 20-so what's broke about that?

Discussion in 'General Glocking' started by Toomas, Feb 11, 2005.

  1. Toomas

    Toomas GMG 5"54calMk42

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    Upon firing, my 10 mm Glock 20 will often double or triple (sometimes more) fire upon the initial squeeze. I've put many, many thousands of rounds through this piece since 1990 and I am don't think it's me (ex Naval Gunner so I think I know what I'm doing). Some shops say "so what's broke about that?", and "do you want to sell it?". No! I do not want to sell it and I am able to control the multi fire well at even 50 yards, but the ranges won't let me shoot it. I've heard that it could be a crack in the receiver but I cannot detect one. Anyone heard of such a thing? Suggestions?
     
  2. Rob72

    Rob72

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    I guess it could be a crack. I would wonder about the trigger spring or a fracture in your FP. Something is not allowing the FP to properly catch & hold the trigger bar. Is the FP engagement on your trigger bar beveled, or does the FP show evidence of cracking at the rear?
     

  3. DannyR

    DannyR Moderator Millennium Member

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    If you've polished the trigger bar and/or connector, you've taken off too much metal. Suggest replacing both those parts, and check trigger bar engagement with the firing pin.
     
  4. VN350X10

    VN350X10

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    I've seen it happen with some of the "super light" triggers that people use for IPSC competition.

    "Gee, how did you get a Glock 18 into the country ?"

    uncle albert
     
  5. Glock-N-Fun

    Glock-N-Fun

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    Toomas,

    Have you ever done a detail strip and through cleaning of the slide parts and frame(trigger assembly)parts?If not try it.Your cruciform on the trigger bar is not fully engaging the firing pin lug properly,or something is restricting it from comming/popping up high enough to properly engage the lug after every shot,could be powder residue.
     
  6. ks40sw

    ks40sw

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    Hi, I think DannyR might have the answer about taking to much metal off. I did that on my G24c and it would fire when I release the slide with the slide release. Also it would consistently give me a burst of 2 or 3 rounds down the range with every pull of the trigger.

    Also note that I had the gun pointed down range when that happen (safty first). I ended up getting a new striker for the gun.

    ks40sw:)
     
  7. Glock-N-Fun

    Glock-N-Fun

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    ks40ws,

    If you do anymore trigger work get yourself an orange armorer's half plate,or cut down a black plate so you can accually see the cruciform and lug engagement.

    Toomas didn't mention doing any mods to his G-20.
     
  8. ks40sw

    ks40sw

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    Glock-N-Fun, thanks for the tips. I did that before I was wiser.;f
    Sorry, I guess I miss that part about no mods on his gun.:)

    ks40sw
     
  9. CanadianGlockFan

    CanadianGlockFan

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    Your trigger bar isn't engaging the striker deeply enough as the slide is going back into battery, so it's slipping off when the barrel locks up again. The simplest fix is to replace the trigger bar.
     
  10. Custom Glock Racing

    Custom Glock Racing I did it first. Millennium Member

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    You dont have enough engagement between the FP tang and the triggerbar.
     
  11. Glock-N-Fun

    Glock-N-Fun

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    Toomas,

    When you detail strip and clean the lower,replace the trigger spring with a new one also.The trigger spring is what powers the trigger bar upward after each shot for proper trigger reset.
     
  12. Toomas

    Toomas GMG 5"54calMk42

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    Thanks for all of the suggestions and tips-here's some additional info:
    1.No mods have ever been made to this piece,and in general it still looks fairly new. I clean it very well after each trip to the range, and use Breakfree CLP on all friction surfaces-just enough to keep it lubed without excessive buildup. I'm actually quite amazed at how good it looks after 15 years and 10,000+ rounds...
    2.No polishing of the trigger bar has occurred-detail slide stripping revealed zero/minimal buildup of debris, binding or other flaws. I rarley break it down further than the field strip since it never seems to need much internal cleaning-I only lube these parts with a slightly "damp" patch. I haven't detail stripped the receiver group yet (looks and seems to operate as clean as a whistle) but maybe I will tonight over a couple of beers...
    3.No cracks in the firing pin, springs, or other parts, and no visible irregularities exist beyond what seem to be normal wear.
    4."Sear" at rear of trigger bar is not really "beveled" but has an approx 1/8" wear mark at the top rear with max 1 mil worn away. Engagement tang on firing pin rear shows no defect. How much wear is within the normal operating spec for the "sear" on the trigger bar?
    5.The cruciform on the trigger bar that engages the lug has some slight wear but only on the side, not the top where it engages the lug.
    6.Repeated dry cycling of the slide while depressing the trigger at various depths and speeds does not result in release of the firing pin without first backing off slightly on the trigger (approx 1/4" of trigger release then squeeze does release the trigger). Normal dry firing reveals a smooth trigger action up until the final engagement point where additional pressure results in a crisp release of the firing pin (every time).

    I'm wondering about the trigger bar spring-how much tension should this have? With slide removed and trigger in fired position, and after manually pushing the trigger bar forward by pushing the cruciform, the trigger bar will return rearward but seems weak after the first half of the travel. What's "normal" for this spring's action?
     
  13. CanadianGlockFan

    CanadianGlockFan

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    This is what an armourer uses the orange /"half" back-plate for, to see exactly how much engagement there is between the leg of the striker and the "sear" on the trigger-bar. If you're getting FA fire out of the pistol, it's a safe bet that the engagement surface on the trigger bar has rounded off to the point where it won't hold the striker securely through the entire firing cycle. If you're going to change the trigger-bar, you may as well change the trigger return spring at the same time.
     
  14. T. Harless

    T. Harless

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    Can you get to a controlable FA dremmeling on the trigger bar? I have no intention, just asking.
     
  15. W Turner

    W Turner

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    T Harless.....

    I can't say for sure that you can, but I did some polishing on a G17 one time and took too much metal off the trigger bar/crucifrom and mine would reliably give me 2-3 round bursts until I replaced the bar. Made for some fun times at the IDPA match it happened in though...lol.

    Bull
     
  16. Glock-N-Fun

    Glock-N-Fun

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    Toomas,

    Another trigger spring test you can do is to remove the slide,push the top of the connector(the arm that contacts the cam on the bottom side of the slide) to the left with your thumb,the cruciform should lift upward on the right side as high as it can.If it doesn't your problem might be the trigger spring.If you have never removed trigger bar,housing,spring and connector for detailed cleaning,you may have debri in the housing somewere like the slot in the housing that the cruciform goes through on the left side,not allowing the bar/cruciform to lift high enough.
     
  17. Toomas

    Toomas GMG 5"54calMk42

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    Thanks again to everyone for their help. I detail stripped the receiver but did not find any excessive dirt/debris buildup, but it did reveal that I had excessive wear issues with the sear on the trigger bar as well as some slight stretch on the first loop of the trigger spring, as well as wear on the plastic that the spring hold onto. After the cleaning I did some dry cycle fire tests and noted that if I release the slide from a pulled back position, with the trigger depressed, the trigger would not consistently pull forward indicating that return of the slide under spring pressure would mimic an intermittent FA. Also compared my worn parts to a new G21 to identify the "spec" as opposed to my worn conditions. New trigger bar assembly and springs on order. Once I replace these I'll give it a shot.....
     
  18. Glock-N-Fun

    Glock-N-Fun

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    Toomas,

    Make sure the spring is in correctly,it must look like this when installed (S),not the other direction.The trigger bar is extremely hard and would take a lot of polishing or wear to remove to much metal from the cruciform to promote double's and triple's,i don't think it is as possible as glock owners think it is.I've done a bit of filing and polishing on bars,cruciforms and find it hard to beleive after knowing how hard they are.I think your problem is from something other than wear,probably weak trigger spring,spring in backwards or debri(which you've already disreguarded).

    Good luck
     
  19. otr-ace

    otr-ace

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    The trigger spring in right wrong or out of the gun will not cause doubling problem. Worn out trigger bar or the lug on fireing pin and or the plastic sleeve in the slide which i beleave center the firing pin are the only thing that can cause this. Spring up side down in some cases the trigger will not reset. If the connector is cause then you would be pulling the trigger 2 or 3 times and you just dont realize you are doing it. I have a mod trigger bar that will let you double tap on demand but it will not do it if you dont want it to. The second shot is fired with the trigger but in 6 round string it is about 6 tenth of a second faster than a factory trigger bar.
     
  20. Glock-N-Fun

    Glock-N-Fun

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    otr-ace,

    If you are saying that your gun will fire two rounds with a single pull of the trigger on command,than you have a very unsafe trigger bar,and 6 tenths is not worth jeopardizing safety.If your trigger is performing this way and your were shooting in my squad you would be asked to leave...haha!