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Case Failure (Pic)

kyshootnman

kyshootnman

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Dec 3, 2012
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Greensburg, KY
So I had asked a while back about a ring I was seeing around my 260 cases. I tossed the lot of brass that was showing incipient separation and had one from another lot rupture. It's a very odd looking failure that I've never seen anywhere before. The brass was on its 4th firing, 140 amax with 42.6 gr 4350, neck sized only. The rifle is a Rem 700, Krieger barrel, chambered by a local gunsmith. I'm actually thinking the rifle might have excessive headspace. What could possibly be the culprit of this type of failure?
 

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WOW. Pretty spectacular failure!

If the barrel does not contact the bolt a gage might show correct base-to-shoulder headspace distance although the case isn't supported, allowing the case (like yours) to fail above the web at the MUCH thinner lower case wall. Very common with Glock pistols since the case is not completely supported.

2lvzegw.jpg
 
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Maybe the boltnose counterbore in the tennon is too deep.

First though, I'd check headspace.

Hard to believe its something YOU'RE causing if you've only ever neck sized.
 
I don't think there should have been that much unsupported casehead in a properly set "3-rings of steel" barrel recess/bolt nose clearances. Looks like the barrel recess is a bit too deep, leaving that part of the case unsupported to get that kind of case failure.
 
I agree with you guys. Something definitely isn't right with the chamber. The flared out casing made it apparent to me that that section of the case could not have been supported. I guess I'll take it somewhere else to try to get it properly chambered. If a guy can't do it correctly the first try, I doubt he will be successful the second.
 
turbo54 said:
Maybe the boltnose counterbore in the tennon is too deep.
Click to expand...

Chances are that the headspace is just fine but waaaaaay too much counterbore.

A quick check is to put a small amount of modeling clay on the bolt nose egde, slide bolt closed, pull open, and see how thick the clay is after doing so. Shouldn't be more than a few thousandth's at the edges.

De-grease the bolt nose so it will stick and swab the barrel counterbore with some gun oil to act as a "release" agent.
 
kyshootnman said:
Thanks a lot guys. Your assessment appears to be spot on.
Click to expand...

It won't be a pleasant conversation but I would advise you to talk to your gunsmith about this issue. It is potentially very dangerous, and something that he should know about. He might tell you to go f*** yourself, but hopefully he'll stop and think about what he did, and might not do it to somebody else.
 
I will make him aware, but it's not worth the trouble of proving someone did something wrong. You know how that goes. I already got a face and eyes full of powder from this separation. Lesson well learned. Spend more with a trusted builder.
 
kyshootnman said:
I will make him aware, but it's not worth the trouble of proving someone did something wrong. You know how that goes. I already got a face and eyes full of powder from this separation. Lesson well learned. Spend more with a trusted builder.
Click to expand...

I know exactly what you mean...

A smith, well known to the hide was test firing a rifle that wasn't grouping too great, that was built by another smith known on the hide (though to a lesser extent). Unfortunately, he put a can on it and didn't have eyes or ears on. It blew worse than yours did, but for the same reason. He sustained powder burns on the face and damaged hearing. Luckily nothing else.

The builder was confronted, if for no reason other than to make him aware of it, and hopefully prevent the mistake in the future.

Of course there was the "fuck you" response. Still, he probably won't fuck it up again. This is serious business.

Good luck with it.
 
Another vote for "check the headspace". Might be worth sectioning that and other cases from the same batch to determine how much stretch there was prior to the failure. That could shine some more light on the issue. Out of curiosity, how did the rifle handle the gasses coming out of the back end of the case. Were they diverted away from your face effectively?
 
A good Smith would only need to cut it down however much the counter bore is too deep. Probably between .005" and .100".

At worst, 1" would need to be cut off.
 
kyshootnman,

That is most definately NOT a headspace problem, and this isn't a head separation. I'm on board with the others who have described a seriously unsupported section in the chamber. This isn't a reloading problem, or something that can be resolved with more judicious loads. This is a gun problem, pure and simple.
 
I'm glad you are ok. Thank goodness. I hope you get your rifle up and running soon, as the weathers great. If that happened to me I'd be so uncomfortable/skittish behind a rifle that I'd probably never shoot good groups again!
 
" It's a very odd looking failure that I've never seen anywhere before. The brass was on its 4th firing, 140 amax with 42.6 gr 4350, neck sized only. "

I agree that the only logical explanation is a sloppy chambering job. But this brass had already been fired three previous times? I would expect to see at least some case deformity. Especially if these cases were neck sized only. I think more diligence is called for, and you need to talk to the dude what did it. man up. BB
 
I plan to make him aware of the situation. Legal action or anything of that matter would cost more than it's worth. He does need to know so maybe he doesn't kill someone in the future.
 
It can also be from too much bevel on the mouth of the chamber. Same end result and essentially the same cause...too much unsupported case. Either way, should be a fairly simple fix if the bolt nose is undamaged.
 
I sent the gun off and had it fixed. As everyone had suspected the counter-bore was around 0.040. smh... so I'm rolling again...
 
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