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Glock 19 Gen 4 with a really tight chamber

Discussion in 'Handguns: Autoloaders' started by Tierlieb, Sep 10, 2010.

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  1. Tierlieb

    Tierlieb Member

    Aug 15, 2006
    Hey there,

    I finally managed to shoot my new Glock 19, generation 4, yesterday. It was to replace my annoying CZ 75 Shadow, which has a history of FTEs. And so I was quite surprised when after only some 30 shots (just after starting with mag 3, which contained reloads, the first two were factory loads), I got my first jam on a Glock!

    A cartridge got stuck in the chamber and the slide would not lock. After applying a bit more force than I wanted to, I managed to move the slide and eject the cartridge. It was one of my reloads. It was simply to wide at the back, so it did not chamber properly.

    It is not a problem now that I know, but it was simply unexpected: I expected Glocks to have the biggest chamber possible to work with all kinds of ammunition, even slightly out-of-spec ones. As a reloader, I was more afraid that the Glock might enlarge the cases too much so I'd have to recalibrate them completely all the time, therefore reducing their life time.

    So this comes as a complete surprise. The gen 4 Glock 19 has a tighter chamber than both competition guns that my friend and I tried, and those were a CZ75 Shadow and a Sig Sauer P226, where those loads have been working fine for over a year.

    Has anyone else experienced that? I did not manage to find any posting about this, but being German, I might have used the wrong technical term when searching.
  2. rcmodel

    rcmodel Member in memoriam

    Sep 17, 2007
    Eastern KS
    I'd suggest you full-length size every case, every time you reload it.
    Case life on a 9mm is determined by when the neck splits out, or you lose them in the weeds & gravel, nothing more.

    Without full length sizing, proper neck tension is problematic at best, and may lead to bullet set-back when feeding & resulting high pressure.

    You can also take the barrel out of your gun and use it as a case guage at the reloading bench. Check every round for seating depth and proper chamber fit after you load a batch.

    You can also get a case guage from R.L. Wilson, Dillon's, etc.


  3. Zak Smith

    Zak Smith Moderator Emeritus

    Dec 24, 2002
    Fort Collins, CO, USA.
    Would the offending cartridge fit in a case gauge?

    Did you measure it to see how much it was out of spec?
  4. wanderinwalker

    wanderinwalker Member

    Jan 6, 2003
    SW NH
    I've always believed the Glock's "generous chamber" only applied to the larger-caliber variations. My Glock 17 (Gen 3, about 8 years old) has the tightest 9mm chamber I've run into. It sounds as though yours may be even tighter though.

    Full-length resize and use a case gage. There's a possibility your sizing die may not be working as far down the cases as you think also.
  5. ruckus3008

    ruckus3008 Member

    Dec 24, 2005
    Manassas, VA
    what did you do with your sp-01?
  6. Tierlieb

    Tierlieb Member

    Aug 15, 2006
    Hello there,
    sorry for answering so late, but I wanted to clear this one up because the measurements I got are kinda nice: My friend who owns the P226 got us a chance to measure the chambers of our three 9mms with proper lab equipment. Here is the result, all values given in millimeters, albeit with decimal point instead of comma (to make you Americans a little happy):

    The chamber was measured about 1.5mm after the chamber was completely supported to ensure we were measuring a proper circle.

    First number is the value the computer returned, in rounded brackets are the most extreme measurements that were taken by the system to arrive there.

    Sig P226: 10.013, (10.010 - 10.014)
    CZ 75 Shadow: 10.000 (9.997 - 10.005)
    Glock: 9.955 (9.945 - 9.964)

    Specs for the 9x19 say that P1 (the bottom above the ridge) is to be 9.93mm

    So Glock is within spec, but very intolerant of reloads.

    @Zak Smith:
    Sorry, I do not have a case gauge. I usually follow rcmodel's approach and use the gun barrel as gauge. The last time I was reloading, I did not have the Glock barrel, though.

    Using a vernier calliper, I measure about 9.8 to 9.9mm, definitely no 9.95mm

    Good point about the case life ;-)

    @rcmodel & wanderinwalker
    Full-sizing: I do that. Well, at least as good as I can. I used to use the Dillon die that came with my 650, which severely under-sizes the case in the middle but does not reach down all the way. Last week I bought a Hornady die set, which does not size the middle down that much (ammo looks much nicer now), but even that one misses about 2mm above the ridge.

    That is to be expected, of course: All sizing dies I know have a little funnel at the bottom to ease the case mouth into them. The funnelled part of course does not size the cartridge. Some reloaders I know have therefore ground off material from the bottom of the die to size down even further (but have problems if the case is not perfectly centered by the press). Since Redding does not offer their G-Rx die for 9mm, I am tempted to file off a little, just to improve the resizing process.

    But I am also tempted to have the chamber of the Glock reamed a little wider. Not because I think the fault lies with the Glock, but because I think a dependable gun like a Glock should eat all kinds of ammo.

    I'm going to phase out the SP-01 now that I got the Glock. The SP-01 had two make-overs by members of the German CZ racing team and they have not managed to get it to run reliable yet. That's enough.
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