If I were loading any of the FULL-LENGTH Weatherby cases, (.300, .340, .375, .378/.460) I'd also use F215's in them. I have NOT found it necessary to use Mag. primers in '06-length or shorter magnum cases like the .300 Win. Mag., the .308 Norma,
I also never used a mag. primer in an 06 size case, in way below zero F weather, and i've never had any problems at all...
Drilling Man