Why Magnum primers?

[babaganoush]

What you guys see in those pictures is due to a handloader thinking he can get away with an extra couple of grains over a max load with a bullet that is too heavy. You won't shear off and fragment stocks with a out of battery firing or a slam fire.
LR1955

Thanks for clearing this up. I have seen one KB due to Head spacing issues, and another due to improper hand loads. Both were ugly, and they resembled a couple of the pictures just posted.

While I have not personally experienced or witnessed a confirmed a slam fire event, it just seems to me that by the very nature of the mechanics involved, the bolt would just about have to be in lockup before the SF would occur.

David