Had a case head separation today...

[Kaldor]

Popped the case head off a 308 case in my AR10 today. 47gr of CFE 223 under a 168 TMK, so just about 2gr under max charge in a LC case. Primers all look like the picture, so this was a pure case failure. Lots of smoke coming out the action. Blew the bottom of the E-Lander mag, mag dumped all the bullets on the bench, and part of the mag bounced off the bench and hit me in the face. Good thing I had shooting glasses on. Gun is fine though. Pulled the bolt, gave it and the chamber a quick wipedown and inspection, and shot another 200 rounds. Worst part was killing the E-Lander mag

Take away? First off, good thing I was wearing glasses. The mag lock/keeper hit me right below the eye. I know alot of guys get really worried about case head separation, and I have had a few now. 1 in 9mm in my M&P Pro, 1 in a 243 Rem 700, and now 1 in my 308 AR-10. In all cases, the pistol or rifles were inspected and were found to be fine. Honestly, this was the worst of all 3 as far as smoke and violence. However, we have to remember that these firearms are designed to hold the pressure of the exploding powder. Honestly the worst thing that might happen is we have to Cerrosafe the chamber to get the brass shell out if the head pops completely off.

 

[barnfrog]

Glad you were not injured. Condolences on the E-Lander.

 

[243winxb]

Glad your ok. Very dangerous in an auto loader. Case head failure, not a separation.

 

[ParallelCode]

How many times had the brass been fired prior to this?

 

[lordpaxman]

Glad you’re ok! The case head, where it failed, doesn’t look like the same place where others have had methods for checking for the thinning of the brass and subsequent case separation. I’m not sure there’d be a good way to check for this failure method.

 

[edwardware]

The case head, where it failed, doesn’t look like the same place where others have had methods for checking. . .

Agree. That's not a head separation in the usual sense.

I suspect that was a bad piece of brass from the first. That area of the case head should be solid web, and the last part of the case to fail.

 

[Charlie98]

Case head failure, not a separation.

That's correct. If you section that piece of brass, you will find a fracture right down through the case head.





That is a pic of some of mine, LC brass fired in my M1a. Those blew out the magazine on mine. Initially, I thought I had it isolated to a specific lot of brass (LC06) but as I worked my way into the other headstamps, it started happening to everything... so much so that I wound up scrapping the entire 2K case lot that I had bought. This was all 'once-fired, prepped' mostly LC brass from one of the major sellers. It could have been a bad piece... pieces... of brass, but in reality, I put it down to contaminated brass because of the variation in headstamps.

Before some of you get excited and say it was the extractor ripping the case head off... no. In some instances of case head fracture, I had the gas valve turned off... as I searched for the cause. It has to be fatigued brass of some manner.

It was this experience that led me down the 'I don't use anyone else's rifle brass but mine' axiom, and, finally, to the 'I'm done with LC brass in 7.62mm.' I know it's everyone's darling at the dance for autoloading .308 brass, but I've had such problems with it, to include pull-down component brass, and brass from factory loaded LC ammos, I've sworn off it.

 

[Charlie98]

For the sake of discussion... this is a classic 'case head separation...' This was with a piece of Korean PMJ surplus, again, fired in my M1a... I didn't even know it happened. My daughter was spotting for me, I fired and knew the shell ejected... I pulled the trigger and nothing. My daughter pointed to the case head laying on the table...



Running a wire down through my fired cases... I was able to detect thinned cases... taking them out of service before they separated. Note that wiring them would not have found an incipient case head fracture... because of the location of fracture, assuming it had a starting point before failing.

 

[Charlie98]

Honestly the worst thing that might happen is we have to Cerrosafe the chamber to get the brass shell out if the head pops completely off.

Actually, unless something significant happens... just running a bronze bore brush up into the stuck case is enough to pull it out.

 

[The Glockodile]

Lake City Brass.

If this was fired through a machinegun, yes...

...that happens more often than you'd think.

The case heads - bases, if that was the proper word for it - are so off kilter on my batch even after sizing, that they never really seat flat on the bolt face.

Holy overgassed early case extraction in a loose chamber, Batman!

They're so badly thinned (stretched) in odd places - that I've relegated 3,000 of them to powderpuff plinking duty...

...for my bolt gun!

 

[Slamfire]

Clearly a case failure, right where you don't want it.

This is another possible cause: Brass embrittlement due to NOx out-gassing out of deteriorated gunpowder. That is a 2007 LC case, just what is its past history? How did you get it, and was it loaded, or a case from pulled ammunition?

I was pulling targets on a 300 yard rapid fire, when two of the targets called "Insufficient", a bunch of gabbling came down the radio, and we were told a rifle had blown up on the line and there would not be an alibi string.

When I arrived on the firing line, the shooting relay was still packing up, and the Match Director and John were arguing. John was hollering he did not produce bad ammunition and waving his arms. Well, something fun had happened!

There were two new shooters on the firing line, they both had AR15's loaned to them by John, and were shooting ammunition provided by John. And by a remarkable coincidence, they both had same malfunction, in their AR's, on the same rapid fire relay. Both of their AR's blew out their magazines.

this is one of blow out cases:









the other case was tossed way out in front of the firing line by a disgusted Match Director. But according to the two shooters, it had failed similiarly to the one I picked up. The two junior shooters were not hurt, given new magazines, they were able to continue shooting with the same rifles.

At the end of the match I found the brass was either pull down, or once fired military surplus purchased from Scharch. Might have been pull down. And when I passed the case around, another shooter there said he had similar failures with 5.56 brass from Scharch.

This is a 1988 LC round, which I pulled the bullet



here are some cases loaded twenty or so years previous, and the gunpowder outgassed enough NOx to cause a lot of corrosion.




nice picture of factory ammunition



Pull down brass got on the market primarily due to the fact the gunpowder had deteriorated to the point, that it was unsafe to fire, or unsafe to store. Some ammunition specialist inspected the lot, and determined based on his written procedures, to scrape that ammunition. Civilians buy the stuff, thinking it is "day old bread", only to find the occasional nasty case failure.

I don't know how to tell the difference between surplus brass whose interior has been embrittled, and that which is still good. I understood Scharch tumbled and polished the 5.56 brass they were selling. So even if you have X Ray vision, the green will be gone. This will always be a risk, and since gunpowder deterioration is something the vast majority of the shooting public does not want to hear, that we are bombarded with information in the in print press telling us gunpowder is immortal, and no one makes money telling us what not to buy, this real cause of case failures is largely unknown.

 

[Kaldor]

I agree with all you guys, this wasnt a traditional case head separation which generally happens above the web. I catch those when I process brass, because even though I have a progressive with a case feeder, I still size and trim every piece of 308 brass by hand. Ive tossed more than a few that I suspect are getting weak, as I can see a hairline crack starting to form after I tumble them. Even still, Im not incredibly worried about a true case separation. They are generally just pain in the neck, not super dangerous.

Glad you were not injured. Condolences on the E-Lander.

Yeah, that was a bummer. But they are strong mags, and I have no doubt if it would have been a polymer mag there could have been a bit more "shrapnel"

How many times had the brass been fired prior to this?

At least twice. I have about 5000 pieces of LC 7.62 with various shot counts on it, probably from 2-5. It all started as "once fired" when I bought it, but we all know how that weighs out. I know some of it was truly once fired, but was clearly run thru a machine gun as it took alot of work to get it back into spec to actually shoot. But some of it was obviously sized and shot before as the primer crimps were removed and it sized much easier.

That's correct. If you section that piece of brass, you will find a fracture right down through the case head.

View attachment 1080282

View attachment 1080283

That is a pic of some of mine, LC brass fired in my M1a. Those blew out the magazine on mine. Initially, I thought I had it isolated to a specific lot of brass (LC06) but as I worked my way into the other headstamps, it started happening to everything... so much so that I wound up scrapping the entire 2K case lot that I had bought. This was all 'once-fired, prepped' mostly LC brass from one of the major sellers. It could have been a bad piece... pieces... of brass, but in reality, I put it down to contaminated brass because of the variation in headstamps.

Before some of you get excited and say it was the extractor ripping the case head off... no. In some instances of case head fracture, I had the gas valve turned off... as I searched for the cause. It has to be fatigued brass of some manner.

It was this experience that led me down the 'I don't use anyone else's rifle brass but mine' axiom, and, finally, to the 'I'm done with LC brass in 7.62mm.' I know it's everyone's darling at the dance for autoloading .308 brass, but I've had such problems with it, to include pull-down component brass, and brass from factory loaded LC ammos, I've sworn off it.

I couldnt get a good pic of the inside of the case without getting out a borescope, but yep, the base is clearly fractured and you can see a couple of cracks in the base when you look inside.

Clearly a case failure, right where you don't want it.

This is another possible cause: Brass embrittlement due to NOx out-gassing out of deteriorated gunpowder. That is a 2007 LC case, just what is its past history? How did you get it, and was it loaded, or a case from pulled ammunition?

I was pulling targets on a 300 yard rapid fire, when two of the targets called "Insufficient", a bunch of gabbling came down the radio, and we were told a rifle had blown up on the line and there would not be an alibi string.

When I arrived on the firing line, the shooting relay was still packing up, and the Match Director and John were arguing. John was hollering he did not produce bad ammunition and waving his arms. Well, something fun had happened!

There were two new shooters on the firing line, they both had AR15's loaned to them by John, and were shooting ammunition provided by John. And by a remarkable coincidence, they both had same malfunction, in their AR's, on the same rapid fire relay. Both of their AR's blew out their magazines.

this is one of blow out cases:

View attachment 1080287

View attachment 1080288

View attachment 1080289

View attachment 1080290

the other case was tossed way out in front of the firing line by a disgusted Match Director. But according to the two shooters, it had failed similiarly to the one I picked up. The two junior shooters were not hurt, given new magazines, they were able to continue shooting with the same rifles.

At the end of the match I found the brass was either pull down, or once fired military surplus purchased from Scharch. Might have been pull down. And when I passed the case around, another shooter there said he had similar failures with 5.56 brass from Scharch.

This is a 1988 LC round, which I pulled the bullet

View attachment 1080291

here are some cases loaded twenty or so years previous, and the gunpowder outgassed enough NOx to cause a lot of corrosion.

View attachment 1080292


nice picture of factory ammunition

View attachment 1080293

Pull down brass got on the market primarily due to the fact the gunpowder had deteriorated to the point, that it was unsafe to fire, or unsafe to store. Some ammunition specialist inspected the lot, and determined based on his written procedures, to scrape that ammunition. Civilians buy the stuff, thinking it is "day old bread", only to find the occasional nasty case failure.

I don't know how to tell the difference between surplus brass whose interior has been embrittled, and that which is still good. I understood Scharch tumbled and polished the 5.56 brass they were selling. So even if you have X Ray vision, the green will be gone. This will always be a risk, and since gunpowder deterioration is something the vast majority of the shooting public does not want to hear, that we are bombarded with information in the in print press telling us gunpowder is immortal, and no one makes money telling us what not to buy, this real cause of case failures is largely unknown.

History is hard to say. I have a bunch of it and I dont track firings due to that. I know it was all fired at least once when I got it as it shows the obvious signs of being fired. I also will not buy prepped brass for that exact reason as I want to get a general idea of what its done before. Its easy for unscrupulous brass processors to pass something off as once fired if its all shiny when you get it. Those are crazy signs of corrosion and mine looked nothing like that. I generally only keep 1000 rounds loaded on hand as I worry about corrosion from modern powders and bullets potentially cold welding themselves into a case causing pressure issue.

 

[jmorris]

Honestly the worst thing that might happen is we have to Cerrosafe the chamber to get the brass shell out if the head pops completely off.

A bronze brush pushed into the case can pull them out. You know like if you shove one down the bore, you have to go all the way to the end so they can exit the bore before they can fold the bristles the other direction, to come back out. Pushed into the case they can pop them right out.

 

[JT-AR-MG42]

I guess I'm lucky - so far.
I've experienced my share of head separations in semi -auto .308s and experienced a vertical
case head failure (from the primer pocket, thru the case head, and up the body) with old factory .270,
but have never seen a failure like the OP and several of you have shown.

I do thank you for sharing the photos.

JT

 

[The Glockodile]

https://www.brownells.com/gunsmith-...emovers/broken-shell-extractor-prod23311.aspx

Brownells will take your money for a problem like that!

 

[Jim Watson]

There were two new shooters on the firing line, they both had AR15's loaned to them by John, and were shooting ammunition provided by John. And by a remarkable coincidence, they both had same malfunction, in their AR's, on the same rapid fire relay. Both of their AR's blew out their magazines.

Did that happen several years ago at the range on Arnold Development, Tullahoma, Tennessee?
I was hanging around waiting for the shift from XTC to F class when the hullaballoo started.

 

[Charlie98]

I also will not buy prepped brass for that exact reason as I want to get a general idea of what its done before. Its easy for unscrupulous brass processors to pass something off as once fired if its all shiny when you get it.

I don't know if 'unscrupulous' would be the right word. Mine was from Scharch (Top Brass.) I understood when I bought it that it would likely be machine gun fired. Remember, though... when the DOD sells fired brass, it is sold as 'scrap,' not as 'once-fired brass.' The difference is minute, but significant. I have a couple of threads over on the M14 forum about this very episode... when I was in the Army, I worked in the recoverable warehouse. We used to have barrels and barrels of fired brass... everything from 9mm, to 50BMG and machine cannon cases... all just dumped into barrels or whatever the recovering entity had at hand to put it in and turn it back in at the ammo point. That brass was stored outside in the elements, sometimes for years, before it was disposed of. I think the brass I had was stored in a contaminated barrel (or container...) or was stored in an atmosphere that was destructive to the brass. I don't necessarily blame Scharch. There were other headstamps beside LC in the 2 1K case lots that I bought... WMA and PMJ primarily. I'm actually still using the PMJ; outside of that single case head separation noted above, I've not lost one PMJ case in about 3 firings, although I'll be retiring those cases after the next round. The WMA cases ALL developed case splits, lengthwise up the cases... I put this down to either too hard brass, or work hardened brass. I have cycled those out already.

 

[The Glockodile]

Its easy for unscrupulous brass processors to pass something off as once fired if its all shiny when you get it.

I fell victim to one of those.

Guy "just came back from the sandbox," "needed some cash in exchange for once - fired brass."

Tumbled brass gets all the telltale signs of case failure burnished away.

Mine were overtumbled, probably in a cement mixer, with the case lips having been peened.

I thought I could polish some turds for semi - decent plinkers.

I bought them for my AR - 10.

Thankfully I started off with my bolt gun.

Multiple case head separations at the web - thankfully, none 100% circumferential (even if they were 100% circumferential at the web, your bolt gun will likely NOT feel it - there's usually enough obturation to seal the explosion).

 

[ms6852]

My condolences on your magazine but most import thank God you were not injured. Lot of pressure generated by a round inside a chamber. I had my first experience with case head failure on a 10/22. Took me by surprise as how much force was inside that little 22 round. Glad I was wearing my glasses too. I imagined if it it would have happened with a large caliber round I would have had to place my unmentionables in the wash cycles several times.