I've blown primers with normal 308 win data using that military IMR-4895 mentioned above, so it's not just temperature swings that cause trouble. There's also a tolerance in slow vs fast burning lots of the same powder.

In the world of statistical variation, if you do something long enough you'll stumble across the worst case scenario and something happens.

Mix an upper end (say the heaviest possible charge of the run) of fastest burn rate powder in a least possible capacity case. Maximum diameter bullet seated with a primer with maximum compound touched off with your hardest trigger squeeze..on a hot day.

It's hard to say what really happened here. Was the metal inherently flawed during manufacturing? Who's to say?

I'd like to think I'm a little wiser now than in my younger hot rod reloading days. Yes the hotter loads tend to burn cleaner and are often the most accurate, but at the same time I prefer to use no more resources than necessary to get the job done.