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Anybody know what causes this problem?

Discussion in 'Handguns: Autoloaders' started by cstarr3, Mar 3, 2013.

  1. cstarr3

    cstarr3 New Member

    Jan 15, 2012
    Hi all,

    I have recently completed a small Glock project: I bought a 20 slide, parts, barrel, etc, and put them all on my Glock 21 (which I bought with the intention of modifying it). The firing pin spring is a little light (4 lbs, as opposed to the standard 5 lbs), as that is what was available at the time I made the purchase. I have also bought a 9x25 Dillon barrel.

    I have now tested out both barrels and have had a similar problem with both; there is an occasional trigger pull that does not result in the intended BANG! This is far more prevalent with the 10mm (shot up a box of PMC hardball range ammo) than with the 9x25 (used DoubleTap, 147 gr). In fact, with a loaded magazine of 10mm, half of the rounds tend not to fire. I reload the 4 to 6 that don't fire back into the magazine, and again about half of them fail to ignite on the next go-around. So then I put the two-or-so back into the mag, and then, third times a charm, they fire. So to shoot 10 rounds, I have to load the equivalent of about 17 rounds.

    In the entire box of the 9x25, one cartridge just would not fire, but the problem is not quite as pronounced, usually with only one round per mag (on average) not firing. In the 10mm, all of them eventually went off, but the rate of failure was far higher; I had to pull the trigger probably 80 times or more to fire 50 shots. In any case, I am still disappointed with the results. So I thought I'd get some input from some gun-types, and see if any of you have had similar problems with Glocks that have had newbie modifications done to them.

    I have a sneaking suspicion it might be a firing pin spring problem, or even a pin safety problem, but let me know what you guys think.

    And for those who are curious, no, I am not a gun smith, or an experienced machinist. I am just a dude who wanted to try his hand at doing something he thought would be neat.
  2. BRE346

    BRE346 Member

    Feb 10, 2011
    South Texas
    Glock mod?

    It can be fun to try this or that with a gun....as long as its not intended to defend your life.

    The firing pin spring is what slams the firing pin into the cartridge primer. If it's weak you get the trouble you describe, fail-to-fire. The stronger spring will cure that.

    I've noticed stronger firing pin springs in a coupla guns meant for tactical use.

    Another thing. The firing pin, its chamber and hole must be whistle clean and dry. Only dry lube, if any, should be used.

    I think older hands will agree with me.
  3. bds

    bds Elder

    Jan 10, 2010
    Northwest Coast
    I am assuming all the ammo used were new as primers that fire on second or third strikes are due to primers on reloaded rounds not seated deep enough or primer cups too hard (say, rifle primers used instead of pistol primers).

    +1 to above post.

    I would do the following:

    - Take the slide off, remove the barrel and point barrel end down
    - Depress the firing pin block while watching the firing pin slot
    - Firing pin should drop down the rectangle slot fully until the block hits the back of the breach wall

    If it doesn't, remove the slide cover and inspect the firing pin and tube for fouling build up. Clean as necessary. If the slide has seen several thousand rounds and has not been cleaned, you may have hard caked on fouling build up behind the breach wall of the slide (that will prevent the striker pin from moving forward) which may require soaking the bottom of striker tube with Hoppes #9 for 10-20 minutes and/or scraping the hard packed fouling build up with a flat head screwdriver.

    Once the striker pin and bottom of striker tube have been cleaned and dried (do not put any lube inside!), reassemble and repeat the striker pin drop test.

    If this does not fix the light primer strike issue, you may have weak striker spring.

    Last edited: Mar 3, 2013
  4. cstarr3

    cstarr3 New Member

    Jan 15, 2012
    Thanks to those who replied.

    I replaced the 4 lb. firing pin spring with a 5 pounder. I took it to the range and went through 50 rounds of Armscor 10mm, and every bullet fired when I squeezed the trigger. I guess light strikes come with light firing pin springs.
  5. Fire_Moose

    Fire_Moose Member

    Dec 31, 2012
    Makes sense.

    10mm is large pistol primers right? I'd expect those are harder then SPP.

    Sent from my CZ85 Combat

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