t-star said:i don't know about your part of the country, but we tend to pay a premium by a couple of bucks for the word magnum- however winchester says "FOR STANDARD AND MAGNUM LOADS"- which infers that it's possibly a standard primer, or a magnum primer, or something somewhere in between- the only real way to tell would be with a pressure chamber and a specified powder charge and see if it generates extra pressure over a standard primer-