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

[lazyengineer]

StH:

You are describing an out of battery firing to the letter. Have had it happen to me twice with the Grendel. Not once with any other cartridge.

If you didn't bump that one piece of brass enough, maybe that is the cause. Or have a bullet seated a bit too long. Could be it short cycled just a tiny amount.

The problem with out of battery firings is no one can ever find out exactly why.

I doubt it was overcharged although I doubt I would go with over 29 grains of 2520 with the long bullets.

Join the club.

LR-55

With respect - I am starting to suspect this is one where the manufacturer cut the brass where web head is cutting it close in depth to the chamber exposed section to maximize volume capacity, with metallurgy and practice that lossens up over time with multiple hot loads. Almost every kaboom here is a Lapua or Starline multi fired case - always looks like OOB - A kaboom type and route that basically never shows up in 5.56 in same platform. AR15 is hard to OOB.

I've seen way too many of these kaboom posts - always lapua or starline