I use 300 Win mag brass to make my Mashburn cases. Donuts come with every brand I’ve tried. Gauge pins tell me when they arrive, usually after 1st or 2nd loading. Ream them out once and they don’t return. It’s a great round but if I was starting over I’d do the 7 Practical to eliminate some steps in case forming.

Last edited by John55; 01/31/21.