Overpressure?

[ROLEXrifleman]

I'm with bigedp51 on this one. I get primers that look like that sometimes with loads that are well within safe operating pressure. Don't confuse cratering with flattening if primers. Ctratering occurs when the primer forms around the firing pin flattening actually pushes the firing pin back and then forms around the breech face. Much greater pressure in one over the other. Then we have the issue of unsupported chambers. Glock oem pistol barrels are notorious for leaving behind "guppie bellies" on brass. When the brass is fired it stretches one way beyond the scope of its initial forming, then it is resized back to spec and stretched another way. If the sizing die doesn't go all the way down it actually leaves a section of unsized stretched brass down there. Either way the brass is already weaker than when new. Now, fire it again from an unsupported barrel and you have the possibility of this happening. Mix in a hot load or bad loading habits and kaboom!

does your carbine have an un supported barrel? If not then it was an out of battery detonation, but that's not likely.

 

[Leadeye]

I'm inclined to say no over pressure based on the primers. My experience has been at high power levels the primers fill and flatten in the primer pocket. I ran up loads for the 357 DE in the 80s that filled and flattened primers, way over book, but that's a really strong gun for .357. Maybe a weak case, or out of battery.

 

[d.kaufman]

Guess im not 100% on the unsupported barrel. Heres a couple pics. 1 with rifle folded and another as best i can do looking in with rifle closed and bolt open. Round looks to sit in chamber just as much as my shield, g19, and hk p30

I know the old glocks in 40 had an issue but i thought thats long since been resolved

 

[d.kaufman]

I'm with bigedp51 on this one. I get primers that look like that sometimes with loads that are well within safe operating pressure. Don't confuse cratering with flattening if primers. Ctratering occurs when the primer forms around the firing pin flattening actually pushes the firing pin back and then forms around the breech face. Much greater pressure in one over the other. Then we have the issue of unsupported chambers. Glock oem pistol barrels are notorious for leaving behind "guppie bellies" on brass. When the brass is fired it stretches one way beyond the scope of its initial forming, then it is resized back to spec and stretched another way. If the sizing die doesn't go all the way down it actually leaves a section of unsized stretched brass down there. Either way the brass is already weaker than when new. Now, fire it again from an unsupported barrel and you have the possibility of this happening. Mix in a hot load or bad loading habits and kaboom!

does your carbine have an un supported barrel? If not then it was an out of battery detonation, but that's not likely.

The feed ramp in these is made out of plastic and is now broke. Im not sure if feed ramp broke because of the round blowing out the case or if the broken feed ramp could of possibly caused it to fire out of battery?

 

[King31]

Guess im not 100% on the unsupported barrel. Heres a couple pics. 1 with rifle folded and another as best i can do looking in with rifle closed and bolt open. Round looks to sit in chamber just as much as my shield, g19, and hk p30

I know the old glocks in 40 had an issue but i thought thats long since been resolved

If that round is full chambered, I would definitely say it is not fully supported. Part of the body of the brass is not into the barrel leading to my reasoning. I load for both my glock .40s, but always use a push through die and then also full length resize.

 

[d.kaufman]

Heres a pic of the bolt face too. Someone up thread asked about that too for the primer indentations

 

[d.kaufman]

If that round is full chambered, I would definitely say it is not fully supported. Part of the body of the brass is not into the barrel leading to my reasoning. I load for both my glock .40s, but always use a push through die and then also full length resize.

That round is a factory American Eagle 115gr fmj and is not what i was shooting at the time, if that makes a difference. After further calculations as to how many rounds i fired prior to this happening, it was 83rd round. Without pulling barrel in 3 of my 9mm handguns it seems that roughly that much of the case sticks out when looking into the firearm with slide locked back

 

[Wolfhound]

Anyone have any thoughts on the odd marks on the fired cases about 2/3rds of the way up the case?

I have only seen primers flow back like that once. My son bought some "remanufactured" ammo at a gunshow. It way really hot. Probably at or just past max loads and he was getting primers pushing back into the firing pin hole. We tried some of my reloads and the primers looked normal. Same with factory loads. We chalked it up to the gunshow ammo being loaded too hot.

I think the weak or flawed brass theory is a possibility. Maybe combined with really hot reloads.

 

[d.kaufman]

If that round is full chambered, I would definitely say it is not fully supported. Part of the body of the brass is not into the barrel leading to my reasoning. I load for both my glock .40s, but always use a push through die and then also full length resize.

I just pulled the barrels off my g19, shield, and hk p30sk and they all seat the same depth as the sub2000 looks in that pic. I think the pic i took may be a little deceiving, making it look like its sticking out further than it really is. Using the black line on the box this is how much sticks out on all barrels in all 4 weapons. This is a factory round for reference

 

[d.kaufman]

Anyone have any thoughts on the odd marks on the fired cases about 2/3rds of the way up the case?

I have only seen primers flow back like that once. My son bought some "remanufactured" ammo at a gunshow. It way really hot. Probably at or just past max loads and he was getting primers pushing back into the firing pin hole. We tried some of my reloads and the primers looked normal. Same with factory loads. We chalked it up to the gunshow ammo being loaded too hot.

I think the weak or flawed brass theory is a possibility. Maybe combined with really hot reloads.

Those were the only cases that had those marks. The marks pretty closely resembles the chamber of the barrel. Im almost starting to think the cheap plastic feed ramp cracked and then broke completely on that final round causing it to fire somewhat out of battery?

 

[Wolfhound]

Those were the only cases that had those marks. The marks pretty closely resembles the chamber of the barrel. I am almost starting to think the cheap plastic feed ramp cracked and then broke completely on that final round causing it to fire somewhat out of battery?

The marks are kinda odd. If the round was fully chambered when it fired the side of the case would have been supported and couldn't have pushed out like it did. Seems to point to either unsupported or out of battery.

 

[d.kaufman]

The marks are kinda odd. If the round was fully chambered when it fired the side of the case would have been supported and couldn't have pushed out like it did. Seems to point to either unsupported or out of battery.

Thats kind of why im thinking now that the feed ramp was cracked at first on the rounds the didnt blow out the case and they were whacking the the throat as they fed into the barrel and then ramp completely broke and round fired out of battery? No other damage anywhere on the firearm other than the feed ramp was broke in 2 pieces. The ramp portion being 1 piece and the other piece that basically locks it in place under the pin.
Ordered an upgraded Mcarbo ss feed ramp along with some other parts(buffer, trigger springs, hardened pins).
One thing for sure is I will never use reloads, other than mine, again.

 

[ROLEXrifleman]

Ibdid my best tobyry and show supported chambers vs non. From left to right:
TROS 9mm ar barrel, non supported
OEM Beretta 92, non supported
LW G17 aftermarket barrel, supported

 

[d.kaufman]

View attachment 64084

Ibdid my best tobyry and show supported chambers vs non. From left to right:
TROS 9mm ar barrel, non supported
OEM Beretta 92, non supported
LW G17 aftermarket barrel, supported

Im guessing then that the sub2000 is unsupported. This is the best pic i can come up with

 

[Bookmark]

Here is my Ruger American
and my CZ 75B

Both with a factory round in the chamber.
Your photo skills are much better than mine. Lol

 

[d.kaufman]

Guess im really not much closer to figuring out what happened. Weak case, Overpressure/overcharge, out of battery(if so why) etc. Guess im gonna do some upgrades and then run some factory ammo thru and see how she runs

 

[Ericpwp]

Weak brass gets my vote. The primer doesn't look flattened at all.

 

[dugsagun]

As others have said, definitely looks like an overpressure round for sure. If u are looking to still get some use, pull the bullets. I have in the past had to pull some bullets from some 357 loads i got cheap at a gunshow.

 

[d.kaufman]

As others have said, definitely looks like an overpressure round for sure. If u are looking to still get some use, pull the bullets. I have in the past had to pull some bullets from some 357 loads i got cheap at a gunshow.

There was only 1 round left from the ones i got
Already pulled the bullet, basically just to disable it. Threw away the case as im not sure if that could be the issue also. Will reuse the hp bullet but the rest garbage as far as im concerned. No more reloads other than mine anymore, thats for sure

 

[ROLEXrifleman]

At the end of the day if you're looking for root cause I'm pretty confident saying it was the ammo. A non supported chamber is not an issue in and of itself, in this case though I believe it helped expose bad ammo that otherwise would have flown under the radar.