Why Magnum primers?

[Nukes]

Not to mention a good face.
One should also be careful using WSR primers. There is a higher incidence of slam fires with the new WSR primers. Apparently the new copper tinted primers are a lot softer than the older chrome colored ones.

Interesting that the current (9th) edition Hornady Reloading Manual uses WSR primers for the 6.5 Grendel information.

Other than a general statement recommending magnum primers for magnum cartridges, the Berger Reloading Manual 1st Edition does not specify primers for any of their loads.

Thousands and thousands of rounds in Service Rifle practice and matches and I have never experienced a slam fire or piercing! I use FGMM primers in my match rounds. I certainly dont doubt it can happen, but this is one reason I think the use of Titanium firing pins is worth the extra $$. All of my Match rifles use them, including my Grendel. Only my M4/SBR's have the M-16 type firing pins plus 5.56mm NATO chambers.

Like pburr, despite many thousands of competition and practice rounds, I have never had nor even seen a slam fire—excepting open bolt MGs
;-)

Though I am aware of the claims for faster lock times and fewer (no?) slam fires, are these just theoretical reasons? mere marketing so that we buy $50 firing pins? or is there actual data supporting the accuracy and safety claims?