Posted: 7/13/2014 7:50:53 AM EDT
What causes this?
This is LC brass that was either 1x or 2x fired prior to this firing (I don't recall which batch I was shooting at the time). The load is 23.5gr of Varget pushing a 75gr Hornady BTHP at about 2680fps out of a 20" AR15. I could not find the bottom half of the casing in the tall grass I was shooting in. It looks too high to be a case head separation, doesn't it? I've never had a broken shell before and aren't really sure what causes it. Thankfully, both halves of the broken shell came out of the chamber and simply caused a double feed that was cleared with simple remedial action methods. |
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Quoted:
What causes this? http://i88.photobucket.com/albums/k169/sawgunner711/A62BE90A-F8C8-4CE6-9EDD-0F82FE482741_zps61uaphxp.jpg This is LC brass that was either 1x or 2x fired prior to this firing (I don't recall which batch I was shooting at the time). The load is 23.5gr of Varget pushing a 75gr Hornady BTHP at about 2680fps out of a 20" AR15. I could not find the bottom half of the casing in the tall grass I was shooting in. It looks too high to be a case head separation, doesn't it? I've never had a broken shell before and aren't really sure what causes it. Thankfully, both halves of the broken shell came out of the chamber and simply caused a double feed that was cleared with simple remedial action methods. Looks like a defective case.......but if you want to swing by the shop with the upper we can pull it down real quick and check headspace on the barrel to be sure......... |
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What year is the head stamp? there was a lot of LC brass sold on the market the was new unfired and it was crap. Several people have had problems. 09 and 11 were the worst.
If you are reloading have you checked how far you are setting the shoulder back with your sizing die? Most dies will over size if the die is run down to the shell holder. |
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Quoted:
Looks like a defective case.......but if you want to swing by the shop with the upper we can pull it down real quick and check headspace on the barrel to be sure......... Quoted:
Looks like a defective case.......but if you want to swing by the shop with the upper we can pull it down real quick and check headspace on the barrel to be sure......... Thanks for the offer, but you're significantly north of Savannah, aren't you? I should have a set of headspace gauges anyway, as much as I tinker with stuff. Quoted:
What year is the head stamp? there was a lot of LC brass sold on the market the was new unfired and it was crap. Several people have had problems. 09 and 11 were the worst. If you are reloading have you checked how far you are setting the shoulder back with your sizing die? Most dies will over size if the die is run down to the shell holder. I hadn't sorted the brass by year, and have no idea what year the cartridge case that failed was made. I bought all of this brass advertised as "once fired." I do know though, that when this one failed, it was either the first OR second firing by me. I've got my die set up to bump the shoulder back .002-.003", so that shouldn't be the issue. And if it were, case head separation usually occurs closer to the head of the case. I am, however, gonna get a set of headspace gauges and check that again, even though it should still be fine after the removal/reinstallation of the barrel. |
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yep. looks like the old "incipient head separation" for sure.
plus, if you didn't fire the brass one time yourself, personally, I don't take anyone's word that brass was "fired once or mebbe twice..." Don't get me wrong--I am not casting aspersions or doubting you, but you never know exactly how many times brass was fired unless you do it yourself. 
There's a thread about this in the "Reloading" section with some great pics; Ah! the joys of finding defective cases before re-sizing brass with the old "bent paperclip" trick! Ya unwind a small paperclip; bend the very tip to an "L" shape, just enough to run down the mouth of a case; you run it down the wall of a case all the way to the bottom and if you feel a "wrinkle" inside, it's prolly beginning to radially separate. I call it "tickling" my brass! Incipient Case Head Separation Detection 
P.S. I've had this happen during a tournament up on the line at Camp Perry when the case got stuck inside the barrel. ruined my day! Cheers! |