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

[Klem]

Been here 2 years, this is the 4th or 5th kaboom. The number of kaboom's/user/unit time is stunning. Common demoninator is lapua/starline.

Lazy,

Lapua is all I use in this calibre. No brass failures.

If you have had 4 case separations then I would be looking elsewhere for the reason. I have had two case separations in my shooting career, both on the same day (not Lapua). I knew almost nothing about headspace at the time and that was definitely my fault for bumping them too hard.

For the thread, I agree, we are just speculating without seeing photos of the brass and bolt - and 52's discovery of the bad batch.