AR Sponsor
Posted: 7/23/2009 3:27:52 PM EDT
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While shooting today, I had a round that sounded "funny" right after I pulled the trigger, and the bolt didn't lock back as briskly as when shooting the other rounds I had been shooting. Upon looking at the ejected case, the head showed incipient cracks around one side with evidence of carbon around the cracks...partial case head separation.
In any event, I continued to shoot without any problems, and upon stripping & cleaning I saw no obvious signs of damage to the bolt or carrier. My question is regarding anyone who had a similar experience, and things to be careful to check with the rifle, such as minute cracks anywhere I should be leery of especially regarding the bolt and/or bolt carrier. The AR is going to Perry with me this year. i sure would hate to have an issue. Any help from the hive would be greatly appreciated. 
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Black Hills Blue Box...reloads. What matters is the fact that it happened partially, not a full blown case head separation, sort of like a heat seeking missle that misses a fighter pilot. I got lucky in that nothing was destroyed.
What I'm looking for is information on insidious cracks in the bolt or carrier that I cannot see. Everything worked fine after the shot, and subsequent to the shot. But, this particular AR is going to be shot in competition, and if I need to purchase a new bolt or bolt carrier because of the possibility I might have issues I don't see or know about, I'd like to know now rather than later. Just wondering if someone else out there has had a similar situation, and any problems that came up "down the road" while shooting the weapon as a result. |
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I have had case separations, case splits and neck splits over the years during competition shooting. I never noticed anything wrong with any part of the firearm and continued using the firearm until I replaced the barrel and bolt. I have seen small burn marks on the face of the bolt from gas leaks around the primer pocket when I used WSR primers. Good Luck at Perry! HTH
FWIW the shots fired when I had case separation or neck splits were still on call on the target |
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Yup. Such is the case when you buy 'em. They're less expensive for a reason...
I wouldn't ordinarily shoot them, but with (match) ammo being as scarce as it is I had no choice. Time to get to learnin' how to reload––and get more case head separations––oh yay!!! 
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Quoted:
While shooting today, I had a round that sounded "funny" right after I pulled the trigger, and the bolt didn't lock back as briskly as when shooting the other rounds I had been shooting. Upon looking at the ejected case, the head showed incipient cracks around one side with evidence of carbon around the cracks...partial case head separation. In any event, I continued to shoot without any problems, and upon stripping & cleaning I saw no obvious signs of damage to the bolt or carrier. My question is regarding anyone who had a similar experience, and things to be careful to check with the rifle, such as minute cracks anywhere I should be leery of especially regarding the bolt and/or bolt carrier. The AR is going to Perry with me this year. i sure would hate to have an issue. Any help from the hive would be greatly appreciated. Those incipient cracks....are they in the case head, ie. the portion of the case to the rear of the web, and do they run into the primer pocket and rim? Are they located in the first .200 length of the case measured from the rim face? If so, this is the onset of a disastrous type of failure where the case head actually fails structurally and 50,000 psi, hot plasma pours out into the bolt face, usually vaporizing the primer cup, curling up the extractor claw, goes on back and down inside the bolt and splits the bolt like a log splitter, trashes the firing pin, pressurizes the aluminum shroud around the BCG and splits it, blows out through the mag well, wrecking the mag. etc. On the other hand if the cracks and separation are ahead of the case web, forward of the .200 length, then the hot gases are usually attenuated somewhat by the remaining portion of the separated case, and just shows signs of soot leakage around the OD of the case with minimal structural damage except to the case itself. So, if it was the former, then that is cause for some concern, but it is concern with the ammo, not the rifle. Malformed or otherwise weakened cases with thin webs or other flaws can lead to the former failure. Fatigue stressed cases stretched repeatedly due to resizing, and restretching during max. chamber pressure typically lead to the latter scenario. |
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