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

[DeNinny]

There’s nothing theoretical about the brass being supported in that location. It either was or it wasn’t.

The design of the feed cone and chamber is both theoretical and real. The brass is supported in the chamber area and it is unsupported in the feed cone area. Reality will ALWAYS match theory. If it doesn't, you have one of them wrong.

If the feed cone was the factor, then we should see circumferential and relatively-even failure with a total case head separation.

See my earlier explanation of how the extractor area is literally more open than the other areas with lugs. It literally takes up less space than the lugs. To repeat, that area allowed the brass to expand the most for the blowout round. As such, it failed there first. I would never assume a relatively even failure when the extractor is physically different than the lugs and the metal is stretching to the point of touching them.

Instead, we just happen to see it fail aligned perfectly with axial extractor force.

This is completely explainable by my repeated explanation of it. It's aligning to the location of the extractor. And the blowout location flap is aligning perfectly with the feed cone score line.

We also don’t see evidence of catastrophic failure of the surrounding pressure containment structures and the non-pressure-bearing structures that hold them.

I would suggest more study of AR-15 catastrophic malfunctions, brass yield strength, and what those look like.

We don't see any more failure because the pressure dissipated before it did damage to anything else (besides blowing out the OPs magazine).

The catastrophe occurred at the blowout and it didn't need to be any more catastrophic than this, other than minor damage to the mag and such.

I have studied all of those things and know what they look like. Hence, all my points throughout this thread.