In a kaboom detailed on another forum the owner couldn't understand how it happened because he charged with powder using an RCBS Chargemaster and immediately seated a bullet.

That was I believe Bullseye in a .357 case. The truth is every process is foolproof right up until it's not followed. It's the interruptions by people, malfunctions, or lack of focus that cause these errors. Safety lies not only in the process but also in the protocol for when the process is interrupted unexpectedly.

I'm sure you've loaded for decades without a problem. Me too. I caught myself double-charging a case once after a person interrupted me. I failed to follow my interruption protocol but I realized it almost immediately.

This could happen to anybody.