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

[LRRPF52]

If unsupported area is radiused into supported via feed cone, wouldn't we see some evidence of the brass following the radius rather than be straight to a fissure with only the lower half exhibiting extrusion? I can see a tear causing such a clean slice, but an in battery blowout should be a bit jankier on both sides of the failure point.

It's an interesting thought.... both sides of this, where the only difference really is 1 microsecond of time.

This is the main fact that showed up with subsequent pictures today.

What appears to be the point of the failure node just coincidentally aligns with axial extractor force.

The brass wall ahead of anything related to the extractor position just knew to initiate its failure there, then split the case outwards circumferentially in both directions away from that point radially.

How did it know to initiate the failure node there, and why didn’t it evenly separate the case head?

There was obviously enough internal force to exert gas pressure through the failure node, because it blew out and bowed-out the magazine, blew the floor plate, follower, and spring out.

This is why I’m suspecting early extraction caused by a combo of CLGS, AA2520 hitting the gas port with sufficient port pressure and volume.

An in-battery case failure is bad ju-ju for the action, normally accompanied by damaged-beyond-repair critical pressure containment and receiver parts.

If the action was built with exotic alloys and held together, we should then see the case remnants taking the brunt of the force, namely:

* Case head extrusion over the extractor shelf with mangled presentation (We see the opposite, with otherwise normal case head appearance.)
* Case extrusion into the ejector channel (None appears to be present on the case in question, while I see some very slight ejector channel shadowing on one of the other pieces of brass that had no issue, proving that photographic resolution provided has the ability to show that.)
* Fragments of brass distributed on the bolt face, and inside the extension.
* Primer is often blown or cratered substantially.
* Bolt face receives pitting from propellant blast circumferentially around the firing pin aperture.

A normal action will usually see the carrier and upper receiver split apart or at least blow-out, since high pressure was directed into non pressure-containment parts.

47,000psi is still 23.5 tons of peak pressure.

A peak pressure failure event is not indicated by these pieces of evidence posted by the OP so far.