I had a partial case head separation using a 1.8oz buffer

[LRRPF52]

That flap occurred within the unsupported area. Within the feed cone itself. And it 100% has the room for it, according to my measurements. The feed cone is wide open space for it. And while in battery, it looks like the other half of the flap bent right into the bolt itself and right over the extractor.


Sorry, but the pressure quickly dissipated as the bullet got farther away from the case mouth. And it dissipated at the blowout. As soon as the blowout started, all the pressure started releasing.

And as OP stated, the pressure at that end ended up blowing out his magazine.

I'm very sorry but the more we discuss this, the more likely I see the blowout model occurring instead of the extraction model.

At those pressure levels, far more damage would have happened.

There had to be some pressure relieved, but enough residual pressure to allow gas escaping from the case to participate in the partial case head separation and flow around the bolt.

Earlier case failure isn’t supported by the way everything is presenting, the intact extractor being the biggest piece of evidence.

If you have seen in-battery/over-pressure catastrophic failures, you would see the distinction.