Before I learned to adjust my dies properly, I had a lot of case head seaparations with a 7Mag and full power loads. The only clue you had was when the bolt was opened and only a piece of the case came out. In a lifetime of shooting every week with centerfires and hunting everywhere I can afford, I have had one blown primer and never knew it until I pulled the case out of the box to lube it before resizing.

jstevens,
I agree on your point about measuring case heads.
Primer pockets that stay tight after many loadings is the only criteria I really trust.

For cartridges fired in springy action loads may be reduced significantly below factory and manual recommendations to reduce the chance of a head separation.