Glock 9mm Casings Dented at Mouths

S

Swifty Morgan

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I have been working on a 9mm semiwadcutter load. Today I got back to it. I put 5.6 grains of BE-86 in Starline brass, and I used 125-grain Missouri Bullet semiwadcutters. I'm using Winchester small pistol primers.

I am now happy with my average velocity (1134), but several of the cases I shot today now have bent mouths.

I read that the recoil spring and magazine springs can cause this. My magazine spring seems fine, and I compared the recoil spring to one from another Glock 26. I don't see any problems.

Should I be concerned about this? If not, I am planning to use this recipe to polish off this box of bullets.

The cases seem fine otherwise. It's hard for me to see how a hot recipe could cause this.

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When I pick up my fired brass at the indoor range some don't land on the rubber floor mat I'm standing on but land on the concrete floor others will bounce off the partition separating the shooters before hitting the floor . If they hit just right on the mouth edge they get a flat dinged on the mouth .
It's nothing to be concerned about ... the brass isn't damaged and resizing will round the case back out .

When a case is dented by the pistol , usually on ejection , the ding is more sharply dented in ...not flat across but a small sharply defined crease or vee .

I don't think you have a ejection/pistol problem ...looks more like case hitting floor /wall at just the right angle .
Gary
 
Hmm, I still suspect the case mouth is smacking the gun someplace as it spins out of the ejection port because if I look really closely I can see the start of a crease in the middle of the flat side of the left and right mouth dents.


Swifty,

This is not a defect, but rather is like tuning a load. Some need a stronger recoil spring than others to slow them down a little to eject the case with less vigor. In the 1911, tuning the extractor hook tension or shortening the ejector can help. But I'm not a Glock owner, so I can't say how applicable that would be.
 
Is it consistent to headstamp? I don’t see this a lot with 9mm, but nearly all of my 380ACP look like this, unless I catch them in a handheld brass catcher.

In my experience, if the case hits the pistol with enough force to make that severe a dent, it also has a sharp V. I vote ground induced!
 
"...case mouth is smacking the gun some place..." Yep. Probably the receiver on its way out. And it's not a big deal. The sizing die will fix it with no fuss.
Those dents are really small compared to some firearms.
Lotta battle rifles do it too. M-14/M1A's, as I recall, do it regularly.
 
I agree with gwpercle and UN and believe it could be either of the issues they outline . I see those flat spots on cases all the time , sometimes my cases other time on range pick up brass , I've never really given it another thought . I've always assumed it was either from ejection or landing on a hard surface just right . In either case the brass has always been gtg for the next loading .

Now in Unclenicks outline of the problem . If I were a competition shooter and wanted my firearm tuned perfect for a specific load . I'd look deeper into the problem but for general use , I wouldn't bother trying to figure out what was causing it unless it was causing function issues . Interestingly , If that was happening to cases coming from one of my rifles I'd go on a deep dive to figure it out . First thing I'd do is figure out a way to capture the case right after ejection before it hits anything else . This should speed your evaluation process by eliminating one of the possibilities .

I recently bought one of these and it seems to work OK . If bent/configured just right it captures 80 to 90% of the cases .
https://www.amazon.com/gp/product/B004NLU340/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1
 
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The first pistol I've seen with its own hoodie. :D

Glad it's working. I have one from back in the 80s that has a smaller capture window. Unlike that one, this one straps onto the hand. It worked most of the time, but once in a while a piece of brass would bounce back just far enough to land between the catcher and gun right on my hand. That doesn't exactly help you get through a rapid-fire string with a steady hold, so I finally stopped using it.
 
Swifty Morgan said:
I have been working on a 9mm semiwadcutter load. Today I got back to it. I put 5.6 grains of BE-86 in Starline brass, and I used 125-grain Missouri Bullet semiwadcutters. I'm using Winchester small pistol primers.

I am now happy with my average velocity (1134), but several of the cases I shot today now have bent mouths.

I read that the recoil spring and magazine springs can cause this. My magazine spring seems fine, and I compared the recoil spring to one from another Glock 26. I don't see any problems.

Should I be concerned about this? If not, I am planning to use this recipe to polish off this box of bullets.

The cases seem fine otherwise. It's hard for me to see how a hot recipe could cause this.

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I would guess 5% of the range brass at the P.D. was that way. They were fired from 5906tsw. I always assumed it was how they landed or they got stepped on.
 
These dents look way too uniform for having been randomly stepped on or dinged from hitting the floor. My guess is it’s caused by the pistol that they were fired in. As to what would cause it, your guess is as good as mine.
 
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