Case split in half, bad brass?

[goose_boy]

Was shooting some test loads out of my 16" AR this morning and had an interesting event. I was shooting the first round of the powder charge, I believe it was 24.1gr (.2 under Ramshot's published max) and the LC brass split horizontally between the shoulder and case head. Luckily I didn't get any real gas thrown back at me or anything, but it slammed the next round into the piece of case left in the chamber. It actually helped, I was able to pry the live round and broken case out together off the live rounds rim. The load was 24.1gr TAC, LC brass, 69 SMK and CCI 450. The brass was full length sized with shoulder bumped back .005. Worked up from start load, noticed no pressure signs, primers weren't flattening or cratering and rifle was cycling smooth. The TAC did seem pretty dirty, cases were coming out with a good amount of soot.

So was this just a case of a metallurgic defect, or something I did wrong?

 

[patrol120]

Once fired surplus brass?

 

[wilecoyote]

in absence of and/or aside any other info, I would think that bumping back.005 could be a little bit excessive, in my opinion_

 

[DAVETOOLEY]

Classic case head separation. The other two cases appear to show symptoms of impending separation also.

 

[goose_boy]

Classic case head separation. The other two cases appear to show symptoms of impending separation also.

Dave, the case used for reference is a piece of off brand chi com brass I had laying around. I put it there for reference of where the separation happened, it appears too high for case head separation but I haven't taken the calipers to it yet. That piece of brass is not resized and once fired so I think it must be the pic that makes it look like impending CHS.

It is once fired LC brass, military or not is unknown. I've gotten it through so many different connections and places you never know, but I believe most of it was probably once fired from law enforcement or private ARs.

The bump back of .005 is about .001 to .002 more than this particular rifle needs, but I have another that needs that much to function correctly so I just size them the same. I did this for loading a bunch of pdog rounds in a hurry but I am going to bring it down a bit after this.

 

[DAVETOOLEY]

Have you pulled the second round out of the separated case? If it's a classic separation it will have a sharp edge from being stretched. Still shouldn't happen with one firing.

 

[goose_boy]

Just pulled it apart. There are 3 separated sharp edges on one half of the case, where the gas burst marked the case. The rest was pretty flat or rounded, but the next cartridge slamming into it could've partially rounded some. It did a decent amount of "resizing" to that shell. The piece I have measures 1.232" so approx .518" up from the headstamp is where separation occurred. This seems too high for a case head issue to me,that's why I was thinking a metal defect. Thoughts? Thanks for the help guys.

 

[wilecoyote]

" ...I believe most of it was probably once fired from..."
..The bump back of .005 is about .001 to .002 more than this particular rifle needs, but I have another that needs that much to function correctly so I just size them the same....

I think that in the words above you can find the cause of the failure_ hope can help

 

[BigJW]

If the first firing was out of a firearm with a dangerous ammount of head space you could see this much case stretching and it can fail that far up the case wall. This is just a shot in the dark and only opinion I haven't looked at the other half of the brass.

 

[shoot4fun]

Does not appear to be too high for a case head separation to me. I think there is an illusion with the live round still stuck in the bad case. As Dave said, it should not have happened on a once fired case. Tac, at least the lot I tried, seems to be temperamental. I got extreme pressure signs before I ever hit their printed limits with it. Not saying at all that the separation was caused by pressure; just adding my experience with Tac. FWIW, I just don't load for a gas gun any more.

 

[former naval person]

Toss the rest of the brass. Cheaper in the end than a ruined chamber. Just don't do it again. JMHO

 

[goose_boy]

The rest of the brass is about 4k pieces. All LC once fired. I know I'm shortening the life of the brass by bumping an extra thousandth or two, but on the second firing?

 

[scotharr]

I'd load some more up and shoot it. Check the cases very carefully after you size them: look for the tell-tale prominent rings indicating imminent case head separation. If if looks ok, then I'd shoot them. If you get another separation, then you need to source the problem: your brass, your chamber, or your resizing. Figure this out by
1. Carefully inspect your brass. In addition to an external visual inspection, cut a few pieces in half length-wise so you can better tell the condition of the case head area from the inside.
2. use a GO and NO-GO gauge to check your chamber headspacing.
2. use the proper tools to measure your shoulder bump before and after resizing. I shoot for .002 - .003 of shoulder bump in ARs. .005 will eventually cause case head separations....but not after one firing.

 

[1idCat]

That separation area is typical for .223 brass that is headspaced .008" too short. Yes, they can separate even on the second firing.

A straightened paper clip with a bent tip can be used to feel the inside of the cases that have had the shoulder pushed back too far. You can feel the groove forming on the inside of the case, at about the area your case separated.

Better to check them, than to have another separation.

And get a Dillon or Wilson case gage to set your sizing die correctly. Set the die so that it sets the shoulder back only .002" to .003". That is enough for reliable feeding in an AR, but doesn't overwork the brass.

 

[DAVETOOLEY]

The rest of the brass is about 4k pieces. All LC once fired. I know I'm shortening the life of the brass by bumping an extra thousandth or two, but on the second firing?

What you don't know is what happened on the first firing. And to answer an earlier post of yours, In 40 years of shooting I've never seen just metal failure that runs radially on a case. It's always from stretching. Although very rare I've seen it run lengthwise as that's how the case is formed or drawn.

Now can these be salvaged? You stated you're bumping the shoulder back .005" on a piece of brass. Was that brass shot in another rifle, once fired or .005" on brass shot in your rifle? Start by trying an unsized piece and see if it fits your chamber. If it doesn't run your sizing die down in very small increments until it does function. Then see where you stand on bump length.

 

[goose_boy]

What you don't know is what happened on the first firing. And to answer an earlier post of yours, In 40 years of shooting I've never seen just metal failure that runs radially on a case. It's always from stretching. Although very rare I've seen it run lengthwise as that's how the case is formed or drawn.

Now can these be salvaged? You stated you're bumping the shoulder back .005" on a piece of brass. Was that brass shot in another rifle, once fired or .005" on brass shot in your rifle? Start by trying an unsized piece and see if it fits your chamber. If it doesn't run your sizing die down in very small increments until it does function. Then see where you stand on bump length.

Good point I didn't specify on that .005 bump. It is bumped to .005 short for the chamber on this rifle, it is only about .003 on the other rifle. I guess the brass I have bumped that far will be used only for the short headspaced rifle and set it back less for the longer headspaced rifle. I have the Hornady/Stoney point headspace guage and have measured once fired brass from both for headspace measurements. Thanks for the help guys, didnt realize that extra thou or two would take effect so quickly.

 

[M14 Shooter]

Your brass may have been once fired.But if was fired out of a SAW it could cause the brass to stretch too much.So when you fired it the brass it was weak in that area and separated.

Regards,Mike

P.S. You can probably check once fired brass with a head space gauge set up and see how much the case a grown.

 

[nuclear_shooter]

If you have the Hornady or Sinclair headspace gauges (to measure the headspace of your brass) and a piece of LC brass that was fired in your gun (if you ever fired any factory new LC brass in your gun), you should be able to compare it to the once fired brass you bought and get a good idea of how far you should be bumping the shoulder back.

 

[Ledhore]

I had this happen once, and never saw it again from the same batch of brass. I'm pretty sure that mine resulted from a slightly crushed shoulder, which jammed the round into the chamber hard enough to rip the brass apart during extraction, with the subsequent round getting shoved into the remaining brass. I performed the standard stock bump on the bench and the whole mess ejected.

This was back when I was using an X die, and it's possible that a long piece of brass was introduced to the x die, causing a slight crush to the shoulder. The rest of the rounds loaded from that batch were fine.

Since then, I check all loaded rounds with a case gage.