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Old 09-17-2020, 12:40 PM
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ar15barrels ar15barrels is offline
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Originally Posted by slamfire1 View Post
AR15 OOB's are very rare in comparison to all others, but I am going to say, they happen and are real.
And the OP did say, and did show, a firing pin strike on the primer.
Which can only happen when the case head is against the boltface.
That can only happen when the case shoulder is against the chamber because of the spring loaded ejector denying the firing pin access to the primer when the bolt is out of battery.

So the only way that an AR type gun can OOB via the firing pin is if the ejector gets collapsed/stuck in the boltface AND something is stopping the cartridge from fitting into the chamber AND the firing pin inertia sets off the primer.
That's a pretty difficult chain of events to assemble and is why the AR rotary breech type guns don't suffer from OOB's.

Any other OOB is not going to be from the firing pin.
So now you are looking at bullet tips as the cause and an OOB from a bullet tip hitting the primer of a chambered case means you had some user intervention because it's not possible to get 2 live rounds out of the magazine in normal operation.

Now looking at the OP's high pressure event, you don't get ejector and extractor flow EXCEPT when the cartridge is in battery.
True OOB events have the thinner web of the case yielding at a much lower pressure and therefore the case head's don't flow into the ejector or extractor spaces.

This reason alone debunks the OP's high pressure event being an OOB.
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