What caused this bulge in the 9mm Luger shell case?

[martyd]

9mm Luger Case

I refer to this as a pregnant shell case.

There is a bulge at the base of the case which is quite noticeable.

I appears to me that the case is not chambered all the way when firing.
Which could happen with a full automatic firearm.
OR
There is a defect in the barrel chamber.

I see this fairly often on range brass.

Sorry I couldn't get a good pic from the side.

Any idea what causes this?

285817

[Bazoo]

Maybe a weak recoil spring. The gun is cycling before the pressure drops, coupled with a mark from the slide hitting the brass.

[358429]

My opinion is that brass fire formed to seal the feed ramp. Is there any damage to the mouths or rims of these bulged cases?

Sent from my SM-G930T using Tapatalk

[Dusty Bannister]

Looks like soft brass case that is loaded to higher pressures. Look at the primer and it will appear to be a narrow rectangle, and a tear drop shaped imprint from the firing pin. Usually resulting from higher pressures in an inadequately supported chamber. More often seen in early Glock 40's. What is the head stamp on the case?

[USSR]

Dusty has it. Fired in a Glock.

Don

[Pine Baron]

Dusty and USSR are onto it. Very common with Glocks. Full size die and go.

[downzero]

Maybe a weak recoil spring. The gun is cycling before the pressure drops, coupled with a mark from the slide hitting the brass.

Locked breach guns do not depend on the recoil spring to keep the gun in battery. The spring is just to store energy to push the slide forward and chamber another round. In theory they can be safely fired without the recoil system even installed at all.

[Martin Luber]

Unsupported chamber in a Glock, do not reload these.

[FLINTNFIRE]

Do not reload them is the best advice , was not just glock who made unsupported chambers , do not bulge bust them either there is a weaked section now and all resizing does is try to make it less obvious .

[Dusty Bannister]

I did not want to brand this case as having been fired in a Glock, but just that is where they are commonly encountered in some calibers. This has also been found in inexpensive 380 ACP guns and I would also wonder about some of the pistol caliber carbines since the longer barrels will have higher pressures due to barrel length. Until the OP provides more information, it is only speculation.

Make NO attempt to reload these weakened cases!

[Conditor22]

the Glock bulges I've dealt with didn't have that dent. Looks like it hit something on its way out of the chamber.

[RobS]

Looks like there may be some good expansion at the head and then a ding likely from the ejection port making things look worse or more bulge than what there is.

[DocSavage]

Those cases don't look like any cases I've seen fired from a Glock. Bulge is way to big.

[charlie b]

The 'smile' ding is typical from the cases being hit by the slide. I've had them get that in my 1911's, but, not with that huge bulge.

Now that I ponder the issue I seem to remember similar cases from some M3 submachine guns (also .45acp and 40 years ago).

[Dusty Bannister]

Charlie, that is why I was asking about the appearance of the primer. The older guns like the Thompson 1927, shooting 45 acp had a large firing pin and was quite a bit different from any other impression. Yes, there is a reason for asking these questions when photos are not submitted. And given the fact that these fired cases are from AZ which is pretty warm this time of year, it might result in higher pressures than rounds fired in "normal" temperatures. It would also be helpful to see different views of these cases and also to be told if this is the recovered appearance or after running through a brass cleaner.

[bedbugbilly]

At the easy availability and cheapness of 9mm range brass - why would anybody want to FL size these and use them . . . . toss 'em in the scrap bucket and use a casing that hasn't been stretched out of shape. Not an answer to the OP's question but rather a response to anyone who would consider re-using bulged 9mm.

[reloader28]

Funny, I've reused bulged brass and not had a problem.

[charlie b]

I have as well, just not bulged over that large an area. A bit different with the .45 though, it being a fairly low pressure round with a 'lot' of tolerance in case volume.

9mm I am a bit picky about. Small cases, relatively high pressures. Small changes make big differences.

[gwpercle]

Just run them through the Lee "Bulge Buster" ...takes that belly right out ...
the kit sells for about $20 .
Gary

[358429]

The sharp crease in the brass looks like a case head failure waiting to happen.

I would not reload these, with out a most thorough inspection, which they may not be worth the time.

So...When a pistol is engineered correctly and the slide/barrel are in battery (locked together) the firing pin is capable of striking, and explodes the primer. Pop.

The powder burns rapidly and creates an expanding volume of hot gases, which push equally in all directions.

This seals the brass to the firing chamber, fire forming it, functioning as a gasket.

The bullet is the path of least resistance, and starts travelling, exchanging the energy/pressure from the gas volume into bullet kinetic energy.

Remember : equal and opposite force, the combined energy of accelerated projectile and powder ejecta leaving the gun, is pushing back, ultimately against the receiver or frame, which is in your hand.

This is the basic function of recoil based operation. Limp wrist a recoil operated pistol and you rob the energy required to properly cycle.

The barrel and slide move together a very small distance, then the barrel tips up (or the chamber cams down,depends how you see it) mechanically permitting the slide to unlock from the barrel, allowing the slide to move to the rear and extract the fired casing, and start over again.

The browning tilting barrel used on so many recoil operated pistols is a timing event.

Bang.
The bullet and powder gasses are long gone downrange if the pistol is correctly timed.

The guppy belly happens when the brass fire forms to fit to the feed ramp, and seal the pressure.

(Dummy with a dremel or glock smile, eh whos to say)

You can slow the slides reciprocation cycle speed by recutting the cam angles on the barrel hood/slide interface and or adding a muzzle break to redirect force from the gasses and add muzzle weight, or make the slide heavier, changing the lock/unlock relationship.

I am looking at you 460 rowland, and 9mm major!

Remember the brass is a gasket. Don't ever expect to use a creased metal gasket and have it be as strong and resilient as one undamaged.

That looks like brass I have found that I suspect was 9mm major overloads. That is why I was asking before, to check the rims and case mouths for damage that happens when slide velocities are too high.

P.s. I have attached a link to youtube, a small movie for your viewing pleasure.

Be safe.


---ORIGINAL PRODUCTION INFORMATION--- WAR DEPARTMENT Official Training Film Fundamentals of Small Arms, PART II: Types of Operations T.F.9 1449 ARMY SERVICE FORCES Produced by Army Pictorial Service, Signal Corps

https://youtu.be/vqUgvoVXqg0



Sent from my SM-G930T using Tapatalk

[jim147]

Load them and let us know. I think you will be fine. I have been wrong once.

[oldblinddog]

I’ve had bulges like that in a Marlin 1894 .45 Colt. Bought new in the 80’s. I returned the rifle.

[FLINTNFIRE]

Those who subscribe to the bulge busting , should keep them for their own use , but invariably someone sells them , I have had a bulge busted case split , when I find them I throw in the scrap where any compromised case should be put .

[W.R.Buchanan]

Those cases were NOT fired in a Glock! The Glock Case Bulge looks nothing like that and also it was only done to .40 S&W cases,,, Not 9MM's ! IF anything those two cases look like they were "stove pipes" that got caught between the slide and the back of the barrel. IE: Type 2 Malfunctions.

You don't debulge 9MM's anyway as the case is tapered, and the web of the case extends much farther forward than it did on the early Federal .40 S&W brass. 9MM brass is much stronger than .40S&W brass anyway.

Do not load Federal .40 S&W Brass with headstamps of "FC" or "FC10" as these two series of Brass were where all the problems with Kabooms came from.. Most of this brass has gone to the scrap heap many years ago but some still lurk in the shadows waiting to blow you up, so you kind of have to look at your brass before you load it.

Also all Glocks from 3rd Gen on had the chambers changed so the intersection of the feed ramp and chamber was much smaller so they didn't do the Bulge, and also all ammo makers corrected the design on .40 S&W brass to extend the web of the case much higher so the area of the case that coincided with the feed ramp was beefed up.

Neither of my Gen 3 guns (G35 2007) and (G23 2015) do it. Fired thousands of rounds of both factory and Reloads thru both guns with no issues whatsoever. It is also good policy to NOT HOTROD the 40 S&W round as it already operates at 35,000 psi which is not too forgiving of loading errors. There is absolutely nothing to be gained in the real world by pushing this round. If you want HP ammo for SD go buy some. Hornady makes some good stuff at about $2 a shot.

This subject has been covered extensively over the years on this site and a search will bring up reams of info on it. I first commented on it in 2011 when I first came here, and said essentially the same thing as I wrote above.

Randy

[Outpost75]

Buchanan is correct. Smash and destroy to prevent reuse. Otherwise setting yourself up for Kaboom!

[tankgunner59]

I have bulge busted 40 S&W cases with the Glock bulge and the signature Glock firing pin indent with no problems. But to my understanding 9mm with it's distinctive taper shouldn't be ran through a bulge buster, I would pitch them and move on especially with that dent from what looks like the slide. Just my .02

[reloader28]

You have to use a 9mm Makarov die to de bulge 9mm Luger and yes it does work

[Soundguy]

Dusty has it. Fired in a Glock.

Don

yup.. glocked brass....

[farmbif]

good 9mm brass is too easy to find to load iffy shells, just throw them in the recycle bin and move on. my old gunsmith mentor would have probably said they came out of some cheap junk gun that aint worth fixing because sometimes there is no way to correct a bad design

[matrixcs]

I have seen this bulge when someone has taken a Dremel to the feed ramp in the barrel to get better feeding...One guy at my range managed to blow his gun apart by doing this mod...no support at the back of the case is not a good idea..

[kevin c]

I agree with WRBuchanan. I've shot mostly stock barreled Glocks for years, and have never seen a bulge in 9mm, only 40 S&W, and not my Gen 3 40's.

If those cases are marked from an inadequately supported Glock chamber, the "smile" should be completely symmetric, should delineate the bulged area of the case (which was much more pronounced in the 40 cases I saw), and be aligned directly at the 6:00 position relative to the firing pin mark (which is rectangular with a central dimple in Glocks). If the pic shows all of the mark that can be seen in those two cases, I'd be inclined to think more of dings from hitting the ejection port than of unsupported chambers.

9mm as well as 40 S&W cases can have any bulges removed by using devices that roll the cases between specially ground plates that can do straight wall or tapered cases no problem. The devices wee originally designed with the "Glock bulge" in mind, even though that issue is rare these days. Now folks do it for chambering reliability. I have never heard of a catastrophic case failure from a case reconditioned this way.

[1006]

I am guessing it was fired in an open bolt fully automatic or in a blowback operated Carbine-could have been loaded hot with too slow a powder or could of had a week recoil spring. In either case, my guess is the bolt slid back just a little too soon, before the pressure dropped off.

Another possibility is a Glock scenario where a reduced recoil spring is combined with an increased power striker spring—as the trigger is pulled, the slide is pulled slightly aft, and the cartridge ignites slightly out of battery, at least that is the warning issued by LoneWolf with their extra power striker springs.

[Soundguy]

Hdn't thought about a subgun. guess it is possible.

PS.. a lee 9mm fcd 90860 will also debulge glocked and similar brass. it has a carbide sizer ring for ironing out overzealous crimp attempts.

[Old Caster]

To be sure, the cases need to be measured to see if they are actually bulged because to me it looks like the cases have hit something and put a dent in it. A possibility is a scope mount that hangs over the ejection area making the brass hit it. I have seen brass like this before and it was not bulged. Can you measure them and let us know what the facts are?

[David2011]

Bulged or not, I would be leery of the crease. It’s a head start on a failure point and I would not reload them for myself.

[Soundguy]

Could be ejection port contact.

[358429]

Without seeing close up, perfectly focused, zoomed in, excellent pictures from all angles, eliminating any

source of uncertainty as to the nature of why this brass has an unusual appearance

is a moot point.


Sent from my SM-G930T using Tapatalk