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

[LRRPF52]

When I have talked about bolt face depth with Bill in the past, he was pretty clear that it’s .136” +0.000/-.003” allowable. So a .133” bolt face depth would be allowable, but not a .138”.

If you tolerance-stack a deeper bolt face with a deeper-than-allowable feeding cone, and that case is able to expand that far back, that’s a recipe for making the brass find the path of least resistance.

This brass looks like it did exactly that. One thing I think everyone can agree on is that the brass was not supported in the location where it failed. Had that section of the brass been contained within the chamber walls, it would have just obturated against the wall, then de-obturated a bit when the pressure subsided.

Combined with the fact that he had Failure To Fire/Activate primer malfunctions before with another load (bang-click), and the bolt able to close on a NO-GO gauge, with the extractor still intact, I think we’ve narrowed it down pretty well to dangerously-excess headspace.