Looks like a case head failure due to thin/low web at first glance.
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Looks like a case head failure due to thin/low web at first glance.
Something fast, like H322 or H4198, would have some room left in the case for an overcharge, but I'm not sure it would be able to generate enough pressure for a kaboom.
Sometimes I wonder if the manufacturer was loading pistol rounds and didn't get it all that fast burning powder cleared out of the hopper before running the rifle rounds.
PMC has a really good reputation but I've seen a lot of turnover in manufacturing since the pandemic.
The more kaboomed ARs I see, the more I think Mr. Stoner was a genius. No harm to shooter, which seems typical for the platform.
Andy
55kpsi (.223) is a significant amount of pressure, and the X-Tac is probably north of that given the velocity increase of it over the bronze line.
When the case head/web fails it's happening during that high pressure time.
The web separates, usually starting at the extractor slot, as that's where the head has no support, and the pressure then follows the path of least resistance.
This observation is based on experience and a few investigations that involved ammunition manufacturers' feedback.
A detailed in-person evaluation would be needed to have a high degree of certainty of either failure event, but that looks a lot like a case head failure/separation at web.
Thank you. An impressive reminder of the power that small piece of brass normally controls.