What’s to explain? Unknown brass failure, probably sizing out of spec (someone else loaded these)
We still don’t have it apart. It’s soaking in Kroil.
You can’t get enough TAC in a 223 case to cause a blowup, or at least I can’t. You certainly can’t double charge it.
It was Hornady’s top load of 24.7 TAC under a 55 grain SP with a CCI41 primer, seated to the cannelur.
What’s not to believe?
What alternative are you proposing?