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

[DeNinny]

Notice how Lapua Kabooms don't result in much rifle damage; where'as most AR Kaboom's are due to massive overpressure events like barrel obstruction or powder error, and tend to grenade, split the BCG, etc. Lapua Kaboom's, tend to not, because they're in-pressure case-failures that vent the lower pressure, and split much lower in the case body in a manner inconsistent with most other kabooms, because they can fail while still locked (in some BBL's).

To me this is indicative of a more brittle (albeit harder) alloy. It takes less pressure to create the kaboom, especially if there is a weak point. With a more elastic and malleable alloy at the same pressure, the case head expands like a balloon but it doesn't burst before the bullet leaves the mouth. So in order to get this type of alloy to burst, it takes MORE pressure. Relatively speaking.

*Disclaimer Alert* All of what I said is metallurgy theory only.