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Thread: Rounds failing case gauge

  1. #1
    Member martin_j001's Avatar
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    Rounds failing case gauge

    So lately I've noticed I'll have several rounds in a batch fail at the case gauge check. The rim of the case will sit just above flush. Many of these will still fall into a Glock barrel without too much issue, but some will hang it just out of battery. I haven't made any changes that I remember recently on my 650 other than the powder charge (as I went from 147gr to 124gr). Any suggestions as to what to check or where to start? Thanks all!
    Jeff Martin
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  2. #2
    Sounds like you made a big change... the bullet.
    How much full diameter bearing surface do you now have showing in front of the case mouth?
    What is the bullet diameter?
    Versus previous bullet?
    Code Name: JET STREAM

  3. #3
    Member martin_j001's Avatar
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    Quote Originally Posted by Jim Watson View Post
    Sounds like you made a big change... the bullet.
    How much full diameter bearing surface do you now have showing in front of the case mouth?
    What is the bullet diameter?
    Versus previous bullet?
    True, I guess I didn't think of that as that much of a change, at least not to the press. I went from the 147gr Blue Bullet to the 125gr Blue Bullet, so I'd think bullet diameter should be the same, but that could be incorrect. I'd have to get back home and look at my OAL settings for the two different loads and measure the bullet diameters and report back to you.
    Jeff Martin
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  4. #4
    I had these issues recently and it was crimp related. What's your crimp? I also switched from the Dillon crimp die to a Lee fcd and my failure rate is very low now.


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    "Shooting is 90% mental. The rest is in your head." -Nils

  5. #5
    Well, yes, I would assume the same brand were all sized the same diameter.
    And the Blue Bullet 125 gr RN nose profile looks similar to 147/150 RN.
    But I think the first step is to tinker with seating depth. A shorter OAL would get the bullet off the lands... if that is the hangup. You would then need to reduce the powder charge to keep from boosting pressure and velocity. I just ran into that with a change in source for hollowpoints.
    Code Name: JET STREAM

  6. #6
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    What 9mm sizing die are you using? Do you pick up brass at a site that has USPSA Open shooters - in other words, any chance of finding 9mm brass loaded to Major power factor? Finally, there is a 9mm brass supplier that has a "stepped" brass internally that sometimes causes a bulge while reloading.

  7. #7
    Member GuanoLoco's Avatar
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    Most everything has an effect - brass headstamp, brass condition, sizing die, bullet, seating depth & crimp.

    A full length sizing die set all the way to the shell place can be helpful, e.g. A Lee Die or a Lee U-Die (hard on the arms though).

    I little One Shot case lube can help some softer cases size down vs squash out with a bulge during resizing.

    Glock chambers are pretty forgiving. I try to keep (Hundo) case gauge failures to about 5% or less and simply segregate CG failures for use as practice ammo where I don't care as much af a round doesn't fully go in to battery. Most will still work in my experience.

    There is often a strong correlation between some but not all head stamps that fail. Take all your case gauge failures and sort them by head stamp - I bet you will see patterns. You can also sort by severity of CG failure (sticks way up, sticks a little up, can be forced to flush or below but doesn't fall out freely) and test in your gun.
    Are you now, or have you ever been a member of the Doodie Project?

  8. #8
    Sounds like you need to seat you bullet a little deeper.

  9. #9
    Get back to us on COAL.
    #RESIST

  10. #10
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    I would be checking for bulged cases from oversized or too deeply-seated bullets, and I'd be checking my case mouths for crimp issues.

    It's possible you've got some cases that are on the really short side and you set your (taper?) crimp die using cases that were on the long side. If so, you might not be getting a full crimp on the short cases. Hopefully you saved the ammo that wouldn't feed so you can take measurements and figure out what's different.

    I set my taper crimp die to just remove the flare on short cases. You don't want to be squashing the bullet or anything like that, just straightening the case wall.

    Just MHO.

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