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Glock 21 doubling firing

Discussion in 'General Glocking' started by Brian Davies, Mar 25, 2006.

  1. Brian Davies

    Brian Davies

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    Hey Guys,
    First time user. I need some advise. I have a Glock 21 which is one of the older model ( approx. 10 years old.). I haven't fire it much until about a year ago when I joined an indoor range here in Calgary Alberta. After about 500 rounds it started to double fire every once in while. One of the range owners said this was a common problem with the older glocks and he would change some trigger parts and fix. it. Well it worked for about the 1,000 rounds now the problem is back again. I took it back to him and he said he wasn't sure what he did to fix it in the first place so I don't really want him too look at it again. Can someone tell me what the problem is and how it can be fixed?

    Proud owner of a Glock 21 and 23.
     
  2. DannyR

    DannyR Moderator Millennium Member

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    You are experiencing an engagement problem between the firing pin and the trigger bar, requiring replacement of one or both parts.
     

  3. Brian Davies

    Brian Davies

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    Thanks Danny,
    I guess I will have to find a good gunsmith to take a look at it. If you don't mind three more questions.
    1) I read in another sight that if I use reloads I should go to an after market barrel. Why?
    2) If so,what would you recommend.
    3) What would case a casing to not completely eject? I check my loads and they are consistent to .1 grain. Would a lighter recoil spring take this problem away.

    Thanks
     
  4. Viper5194

    Viper5194

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    I wouldnt take it to a gunsmith. Do it yourself. If you can locate the new parts, trigger bar and the fireing pin, it takes all of 2 minutes to tear down a glock, install the new parts and reassemble. It really is easy. only tool required if you dont have a glock tool is a 3/32" punch. Works like a champ. I actualy felt really silly the first time I tore my Glock apart and realized just how easy it was.

    To answer your other questions. As I understand it, Glocks do not have fully supported chambers in the factory barrels and some of the aftermarket barrels do. Reloads are so unpredictable that shooting them in a Glocks unsupported chamber can be a bad thing. Once used brass is weaker than new brass and can give way easier in the unsupported area of the chamber.

    Bar-Sto barrels are fully supported and super nice. i plan on buying one for my G30 when funds permit.


    If you are shooting reloads thru your glock check the cases afterwards for any bulging at the 6oclock position. this would be a sign of overpresure and an unsupported chamber. Brass not ejecting could be from a weak extractor spring or bad etractor...

    Grab a punch and tear into the thing. Glockmeister.com has great prices and detailed tear down instructions. Youll be amazed at how easy it is. i thought building AR's was easy untill i dug into my Glocks.

    http://glockmeister.com/trigger.shtml

    http://glockmeister.com/slidedis.shtml
     
  5. DannyR

    DannyR Moderator Millennium Member

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    No barrels for semi-automatic pistols are fully supported barels. Reloads are fine if they are yours. You know what you have made. You don not know the quality of anyone elses reloads. What you shoud not do is use lead bullets, as they cause a rapid increase in barrel pressure. Glock barrels are designed to enhance the performance of modern, jacketed ammo, not 19th century lead.
     
  6. Viper5194

    Viper5194

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    Why does Bar-Sto claim there barrels are FULLY supported if there not? That would be my entire reason for buying one for my G30...

    http://www.barsto.com/category_main.cfm?ID=GLOCK
     
  7. Brian Davies

    Brian Davies

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    Thanks to both Coach and Viper. I will look at purchasing some new parts and install.
     
  8. English

    English

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    Irv Stone III in person on BarSto's DVD explains that what he means by fully supported is that the support comes all the way back to the web of the cartridge. That is, you can still see the end of the cartridge case apparently unsupported but not as much of it as with a Glock manufactured barrel.

    For what it is worth, this means that the feed ramp is steeper so there is more impact on the bullet as it is driven forward. In turn this means that if the grip of the cartridge case on the bullet is not strong enough then it is more likely to be driven back into the case and that would raise the pressure when it is fired. Yet another example of the universal principle about a free lunch! Engineering is aboout compromises. As Stone says, that does not make Glock's design bad - it is good for its purpose of firing production jacketed bullets every time but it pays for that with a little accuracy and a reduced case life for reloaders.

    I'm still going to buy a couple of BarSto barrels if I can get hold of them in Switzerland.

    English

    PS Lead bullets should definitely not be fired from polygonally rifled barrels. Pressures rise dangerously within relatively few rounds.
     
  9. Joe D

    Joe D Guest

    Gosh, what's "a few rounds"? Would 30,000+ lead bullets be a few?;) I have decided there is something wrong with my Glock barrels. Neither my wife's G34 nor my G35 and G21 can be made to lead.
     
  10. English

    English

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    Joe D,
    The following is a summary of part of what is relevant copied from another post. I have fired thousands of quite hot lead 10mm rounds from a G20 without incident but I wouldn't choose to do it again. Passamanek says that results vary with the lead hardness and crystaline structure but that it is not a "linear" variation. I think that can be translated as not predictable and I think that neither of us has the means to check on the crystaline structure of our bullets. Perhaps we have been lucky. Perhaps you have a fatigued barrel that won't carry on being lucky.

    More importantly perhaps is that you have the secret of which lead bullets with which lube are actually safe in polygonal barrels.

    Read on:

    The experiment on lead bullets is in "The Glock in Competition" by Robin Taylor, Bobby Carver, and Mark Passamanek. Passamanek is the engineer who did the actual work on behalf of lawers who were considering suing Glock. After the results they decided not to do so.

    He writes a section about catastrophic failures and his experimental work. To summarise some of his results, he test fired polygonally and cut rifled barrels with lead, plated and jacketed bullets. Polygonal barrels leaded up much faster than cut rifled barrels but were better that cut rifled with jacketed bullets.

    With a .40 barrel with lead bullets loaded to 33Kpsi (35Kpsi is max SAAMI) after 500 rounds with jacketed bullets the pressure was 33.2Kpsi. With lead it was 35.1 after 100 rds, 38.8 after 150, 41 after 200, and 45Kpsi after 300 rds. 50% over pressure was reached after 335 rounds. He points out that the data is about average but some bullets raised pressure faster and some slower.

    He points out that some bullets leaded worse at lower rather than higher speeds and that grainsize and hardness play a part but that the process is not linear.

    This work was done in a pressure barrel which could not blow up. He then used a standard Glock barrel in a rig that would prevent blowing up and fired 300 round through it until the pressure rise leveled out. He then reinstalled it in a stock G22 and, using the same ammo, it blew up - not on the first round but, if I understand, quite soon after.

    He also points out that some Glocks lead worse than others for no apparent cause.

    There is also a fatigue effect in barrels which are repeatedly stressed with over pressure which results in them eventually failing with a pressure which might be lower than some produced with earlier rounds.

    It is well worth getting the book for this section alone but the rest of it is good as well.

    English
     
  11. 4eyes

    4eyes Provocateur

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    That is a definitive statement that can be partially true and can be completely false. "Don't shoot lead bullets in your polygonal barrel" is a liability statement to protect the stupid and the lazy. Problems shooting lead bullets in polygonal barrels as evidenced in the later post are caused by bullet selection/pressure/bullet speed that exceeds the ability of the fast twist to stabilize the bullet at the twist initiation. If the test mentioned had used 200 gr cast lead 40 bullets at 33 Kpsi, or 200 gr. cast lead 45 acp bullets at 45 acp pressures there may well have been different results to the test, and the results posted confirmed their objective.

    No reasonable reloader, using cast lead bullets, would continue a loading practice that built lead deposits in the bore because the accuracy degenerates with lead buildup. And a poorly conceived cast bullet load may not hit an 18"x18" paper after 15 to 20 shots.

    An example of lead bullets in a polygonal bore: the same cast lead bullets that are loaded to a pressure/speed that will lead the bore in a 9x19 Luger at 1100 fps may be shot without leading in a 357 Sig bore at 1250 fps. High pressure/ high speed cast lead bullets will exibit leading in 9mm, 40, and 10 mm Glock barrels because of the 1/10 twist. While the similar or greater speeds/pressures in 357 Sig and 45 will not have leading because of the 1/16 twist. The greatest benefit of Glock owners buying aftermarket barrels is the 1/16 twist in aftermarket barrels.

    So: if you want to shoot cast lead bullets in your 1/10 twist polygonal barrel--keep the bullet speed at a nominal 1000 fps, or less. Minor PF lead loads are easier to accomplish than major PF lead loads and heavier bullets may be shot safely at higher pressures than light bullets because the lower speed of the heavy bullet will engage the rifling at acceptable levels to prevent lead stripping.
     
  12. English

    English

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    Actually it is more a statement to protect the manufacturer from law suits from the stupid and lazy. But it might be valid even so.


    This might well be true, and I don't deny it, but where is it documented? There are many unsatisfactory aspects to the tests Passamanek performed. He didn't test heavier bullets, lower speeds, or lighter pressure loads. He did run the same tests on cut rifled barrels without he same rapid build up of leading. We are not, as far as I remember, told whether the twist rate was the same.

    Your words "the results posted confirmed their objective" implies that the purpose of the test was to show Glock's innocence. In fact Passamanek was employed by lawyers who intended to prosecute Glock for making a gun that blew up. The test convinced them that it was a futile exercise. Rather than confirming their objective, it destroyed it.

    You know that there are lots of reloaders out there without your level of knowledge and experience and they must be allowed for. I am intrigued by your data for the 9mm relative to the same bullet in the 357 sig though I am not convinced that it is caused by bullet skidding. It takes more energy to spin up a bullet at a faster rate of spin. Pressure for pressure that must slow it down and the difference must come in heat against the surface of the bore. I think that it is this that is melting the surface of the lead and leading the barrel. It would be good to know whether the leading in the barrel continues up the barrel in a way related to the pressure and therefore the accelleration at different positions, or whether it is mainly located at the beginning of the rifling.

    One of the things that I regret about Passamanek's tests is that he didn't test slower heavier bullets because it would be good to know where the limits lie. Unfortunately time and the facillities are expensive and I presume he had a budget to stay within.

    Regardless of my quibbles, thank you for a lot of useful empirical knowledge. It is hard to work our way to truth which is often complex and where we don't have the facilities to do the tests we would like to see done.

    English
     
  13. unclebob

    unclebob DFC, MSM, 13 Air Medals.

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    check the firing pin saftey spring and make sure it is not in there sideways.
     
  14. 4eyes

    4eyes Provocateur

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    My post was not intended to be a primer on reloading lead bullets in a polygonal barrel. It was meant to be a refutation of yours and many other posted statements about; don't, can't, may not, illegal to, KB your Glock, if---you shoot lead in your Glock. I accept the fact that one reloaded round shot in my Glock voids the warranty. If I make a mistake and blow my gun; I won't be crying to Glock for a free fix.

    I am not a proponent of anyone reloading lead bullets for their Glock, HK, etc. with polygonal barrels. I am against untrue definitive statements that are posed sufficiently to become true to the unknowing and the accepting.
     
  15. Joe D

    Joe D Guest

    Perhaps there are lead bullets that cause problems in Glock barrels. I use bullets from two casters, Valiant and Magnus. I have never had a problem with either. When I first read about the lead bullet/Glock problem it did not make much sense to me. I had a conversation with Fred Kart many years ago about what causes leading in barrels and where it starts.
    I loaded some 125 gr. Valiant 9mm bullets to 1050 fps. I fired a hundred rounds and checked the bore with a scope. No lead. I continued this test until I reached 1,000 rounds. There was just the faintest bit of lead in the barrel. A couple of passes with a Bore Snake and all the lead was gone.
    The odd thing is my two Kimbers lead more than my Glock 21.
     
  16. 4eyes

    4eyes Provocateur

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    And? I'd like to know what Fred had to say on the subject.
     
  17. Joe D

    Joe D Guest

    Fred stated, in a nut shell, that leading starts at the juncture of the lands and grooves. That sharp corner is difficult to seal. The Glock rifling does not have that sharp corner.
    I have always tried to use a little common sense when loading lead bullets. I can't see pushing them too fast without a gas check.
    The 9mm load, that works well in my wife's G34, will cause my 9mm conversion to lead after several hundred rounds. I am a little skeptical as to the testing protocol mentioned in a previous post. Why would a conventional barrel not show the same dramatic pressure rise with lead build up that the Glock barrel allegedly did? Some of his results just don't add up.
    I think the bottom line is all lead bullets will cause leading to some degree.
     
  18. Glock-N-Fun

    Glock-N-Fun

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    Hard cast lead is even less of a possible problem.
     
  19. Joe D

    Joe D Guest

    Seems like the two casters I use run in the 18-21 range.
     
  20. Glock-N-Fun

    Glock-N-Fun

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    Bottom line is,if the bullets are made by a reputable company and not made by some Gubber in a backyard,and you clean the glock barrel after at least every 200-300rds,i feel it's safe to use lead.
    But i would say,it's probably not a good idea to use lead in a glock barrel with higher velocity's.