Can bulged 9mm cases be a sign of pressure?

pictures would help. To me, this sounds more like a cycling issue where the base of the cases are not completely in the chamber when fired.

Glocks seem to do this more than other firearms.

If it is just on the one side, I'd say it isn't fully supported in the chamber. You said a lighter load still had a slight bulge.
But I'm not familiar with your gun.

Will it iron out in the resizer die?

It would be unusual for only a couple cases out of a batch of identical charged hand loads to exhibit the bulging of the case above the base as shown on your Photobucket picture due to aberrant pressure. If a case bulges due to pressure during firing it needs some place to expand into and chambers of 9mm pistols are generally fully supported.

9mm cases are usually bulged during the reloading process as the brass is pushed down toward the base from resistance in the sizing die, the expanding die or when the bullet is seated. Fired brass if it was chambered would normally be "ironed out" by the pressure of the round to take the shape and OD of the chambers ID. The bulge in your picture looks like it may just be forward the cartridges base web was, created during the loading process and left there after being fired.

The crater looking primer hit is caused by an overly relieved firing pin channel in the bolt face of your pistol. I have a PT92 who's ammo fired through it exhibits the same cratered look as your picture shows. Below is a picture of a fired case and a close up of the bolt face where you can see that the firing pin channel hole had been chamfered allowing the primer to flow into that chamfer.

Mixed brass, range pickups? Does the same headstamp bulge? Or all brands. To me, bulge and primers look like high pressure. http://www.thehighroad.org/showthread.php?t=665199 The new photo that was added , shows a normal case fired in a large chamber

What I see is a slightly oversized chamber but no case head expansion. The cartridge case is a gas seal not a structural, load carrying member. The chamber and locking mechanism supports the case and prevents it from rupturing.

As little as possible of the case sticks out of the chamber and that which is unsupported is the strongest part of the case.



This is from Chinn's Machine Gun. The amount of allowable case head protrusion is in thousandth's of an inch for most actions, though there were actions that used rebated rims and greased cases and that is what you are looking at in the bottom illustration.




If the sidewall or case head ruptures escaping gas could break the mechanism. Since your case does not show budging through the case head area, you don't have dangerously high pressures as shown in the following pictures:

Dangerously overpressure 9mm





Overpressure 45 ACP





Good brass kept these cases from rupturing but it was a close thing. As you can see the case head has swollen where it was not supported by the chamber. This is a positive indication of dangerously high pressures.

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From the pictures and if you had not mentioned Taurus I would have assumed Glock Gen 1 or 2. However, 9mm chambers even in early Glocks supported the 9mm case pretty well. My first indication of high pressure is the primer but... that isn't always the best indicator as the flash hole is very small and the pressure in a small case affects the case itself faster than thru the flash hole to the primer. If your dies are functioning properly, you believe your loads to be within safe limits I would try new factory ammo. If your having the same indicators your issue lies with your firearms. If you don't have these issues with factory ammo, reduce your loads and if the problem persists I would replace the dies. Just my 1 cent cuz 2 breaks the bank lately. Thanks Obama

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I don't see anything there that I would be worried about. I'd happily load them up again.

As mentioned, the bulge you are looking at is well up from the base, so no worries.

Eventually you will get a split in the mouth or body of the case, and that is when you know that case is done.

What I would be more concerned about is resolving your charge/velocity, which seems way off to me.

4.24gr Titegroup is a book max in the data I have (still plenty safe I'm sure). I'd expect velocity to be well above 1040fps.

I don't shoot a ton of 124gr bullets, but multiple .355 or 356" coated and plated bullets have given me velocities of right about that same range with a charge of 3.8gr Titegroup from a 4.5" barrel.

I doubt the barrel length is going to account for that kind of difference.

I just purchased a Springfield Range Officer in 9mm which has a very tight chamber. I have not had a problem in the past with 9mm reloads but started to experience problems with 1-2 reloads per hundred. I have not case gauged in the past but purchased a Wilson and started to notice a uniform raised circumference like Slamfire's pictures. I purchased a EGW u die and it gets most of the raised area, but not all. Now the problem brass will work in my Glock, Browning, sig, CZ, but extremely tight in the range officer.

Another person that I shoot with started to experience the exact same problems. We shoot at Rio Salado in Az and when brass is picked up it may come from a variety of guns. The best conclusion that we came up with is that someone is shooting 9mm major and we are getting one or two pieces of the brass from that gun.

That all sounds normal/reasonable; it just seems like your velocity is low to me. I think you can take it up some if you want.

This bulge is not in the area that would worry me. Looks like it was fired in a large chamber. Primers may or may not be an indication of high pressure.

I worked my way up to 9mm 124 XTPs loaded to an oal of 1.112 with 4.24 gns of Titegroup

Click to expand...

Your Over max and have shorter length according to Hodgdons, 4.1gr Max at 1.150" .But there data is for Berry's plated. So it may be a little light.

Tightgroup is one of those powders that build pressure very quickly with smaller volume. Unless your measuring every load and all have the same head stamps, I would back of the load if it was me. You need a little wiggle room when using powder dispenser, and mix brass particularly with a moody powder like TG.

Any chance you have a neck tension problem and had some set back accour. A little as 0.030" with TG could run the pressure up to 60k.

DBEAM, just a thought, but how do the cartridges look after crimping? Are you using a seating/crimp die?

I had a case fail in a XDS 9x19 shooting re-manufactured ammo, this round cracked the frame behind the trigger. I would be leery of any brass with a bulge as this brass was likely fired from a partly supported chamber and the case head maybe compromised. If all lines up in another unsupported chamber there could be trouble.