Exactly...Un-supported chamber. The early Glocks did that. But any (mfg) chamber that is not fully supported will cause that.
Yes. Glocks, Colt 1911's, some Baretta's and probably some I'm not aware have an unsupported chamber near the base that causes this. Not a concern for most people unless you handload.Un-supported chamber. The early Glocks did that. But any (mfg) chamber that is not fully supported will cause that.
Could you take a picture of primer indent? (Glock striker indent is very characteristic rectangle)This is a piece of 9 mm range brass I picked up. Any idea what caused this bulge at the base?
Perhaps Gen1/2 40S&W Glocks as by Gen3, Glock had already addressed case base support issue and thightened the chamber dimensions. Gen3 Glock barrel compared to Lone Wolf 40S&W barrel showing good case base support to not induce "guppy belly/Glocked" over expansion (Flared Glock chamber opening tightens right against case immediately past the ramp).Un-supported chamber. The early Glocks did that. But any (mfg) chamber that is not fully supported will cause that.
I didn't know about this, might explain some I run across.These days, when I come across a 9mm brass that requires extra effort to resize, I will suspect 9mm Major brass an
Sorry, I hand deprime the brass as soon as I get home so the primer is long gone. I had cleaned and stored the brass so I don’t even know when I picked it up. Probably within the last two years.Could you take a picture of primer indent? (Glock striker indent is very characteristic rectangle)
I haven't seen "Glocked" brass for quite a few years and when I do see "overly expanded" brass in 9mm/40S&W, they usually have non-Glock striker indent of round firing pin/striker imprint.
Perhaps Gen1/2 40S&W Glocks as by Gen3, Glock had already addressed case base support issue and thightened the chamber dimensions. Gen3 Glock barrel compared to Lone Wolf 40S&W barrel showing good case base support to not induce "guppy belly/Glocked" over expansion (Flared Glock chamber opening tightens right against case immediately past the ramp).
But OP is asking about 9mm case and since Gen1, 9mm Glock barrels had excellent case base support on par with various KKM/Lone Wolf/Tactical Kinetics/BCA 9mm barrels.
9mm Glock barrel compared to Lone Wolf barrel (KKM/BCA/Tactical Kinetics have comparable case base support) to not induce "guppy belly/Glocked" over expansion unless fired out of battery.
Another cause of "guppy belly" 9mm brass is from proliferation of USPSA 9mm Major brass where 9mm brass are shot once and left on the ground/range floor due to overly expanded case base (Think thinned case wall). Sadly these 9mm Major brass are mixed in with other 9mm brass for collection and distribution. These days, when I come across a 9mm brass that requires extra effort to resize, I will suspect 9mm Major brass and will check with tightest chamber barrel I have and if case failed, I will attempt to resize again but will toss for recycling if case fails second resizing.
Reloaders that have to deal with this issue in volume will employ a roll sizer to fix it. I think DoubleAlpha sells one ... expensive.
Yep.Another cause of "guppy belly" 9mm brass is from proliferation of USPSA 9mm Major brass where 9mm brass are shot once and left on the ground/range floor due to overly expanded case base (Think thinned case wall). Sadly these 9mm Major brass are mixed in with other 9mm brass for collection and distribution. These days, when I come across a 9mm brass that requires extra effort to resize, I will suspect 9mm Major brass and will check with tightest chamber barrel I have and if case failed, I will attempt to resize again but will toss for recycling if case fails second resizing.
That,s the famous Glock Bulge from a unsupported Chamber and that is one big reason Glock says not to shoot reloads out of a Glock. My brand new Glock 20 in 10mm did that so I put a KKM Barrel in it and that solved the problem. You can also buy a Bulge Buster die that removes the Bulge but I think it would be iffy at best to shoot it from a stock Glock Barrel.This is a piece of 9 mm range brass I picked up. Any idea what caused this bulge at the base?
View attachment 1206022
Please, this is the "High Road" and let's not perpetuate incorrect information that's already been myth busted several times.That,s the famous Glock Bulge from a unsupported Chamber
That's same legal disclaimer many gun manufacturers run. What do thousands of match shooters around the world shoot in their Glocks on a weekly basis, even Team Glock? That's right, mostly reloads.Glock says not to shoot reloads out of a Glock
If your brand new 10mm Glock 20 caused guppy bellied brass as shown in OP, I sure would like to see pictures to be a believer.My brand new Glock 20 in 10mm did that
signs of unsupported Chamber ... The [FN] 510 is creating the smiles due to its lack of chamber support ... FN barrel doesn’t have enough support
Incorrect again. Bulge Buster is not a die but a kit that uses Lee Factory Crimp Die body to push-through resize the base of case that typical resizing die/carbide ring won't reach - https://leeprecision.com/case-conditioning-tools-lee-bulge-buster-kitYou can also buy a Bulge Buster die that removes the Bulge
OP is discussing 9mm and KKM barrel won't do much for case base expansion as my KKM barrel (Along with Lone Wolf, Tactical Kinetics and BCA barrels) has comparable case base support as factory Glock barrel and it's been that way since Gen1I put a KKM Barrel in it and that solved the problem.
To me, "overly expanded" translates to "thinning" of case wall. Once brass case wall has thinned, no amount of push through resizing or even roll sizing is going to make the case wall thicker again ... Resized case length will likely get longer instead.I'm guessing that removing that bulge is over working the brass some. So my presumption now is that those cases may be more likely to fail in the future with max or near max pressure loads compared to normal cases.
What are your thoughts on this @LiveLife?
Yep, this is the conclusion I've come to. I guess it's good that I have a way to remove the bulge if I really needed to , but I won't be saving any more of these cases.To me, "overly expanded" translates to "thinning" of case wall. Once brass case wall has thinned, no amount of push through resizing or even roll sizing is going to make the case wall thicker again ... Resized case length will likely get longer instead.
What do you use to bulge bust 9mm??I bulge bust all my 9mm brass before reloading. I can do it faster than dropping each one in a case guage. With both my SA 1911's and my Canik having tighter chambers than my other 9's, it just makes every round (almost) chamber. I would like to have a roll sizer, but they are expensive. Every once in a while, I'll get one that is too bulged to go through the buster and get tossed. I wonder what they were shot in.
Yes, this is what I do. I run them thru a Makarov die, but I push them inverted, base first thru the die. Primed or not doesn't matter this way, but you cannot do this with loaded rds. I've bulge busted loaded 40sw and 10mm rds, and I have done a couple 9mm, but the force I have to use getting the 9mm thru the die is too sketchy for me with a loaded rd. If something slips , I don't need a kaboom on my bench.What do you use to bulge bust 9mm??
I have read of some using a 9mm MAKROV SIZING DIE, removing the de-prime pin, and pushing 9mm case thru the die.
...Or push the case completely into the die and knock it out via a punch from the top