I will be loading for a 7mm Remington mag with Nosler Brass. I am trying to decide between Federal 215 Primers or CCI large rifle magnum primers. Just wondering if there would be any difference for long range accuracy?
They can make a difference, check out the following webpage that did a primer strength test. Primer Testing Reference
I'd recommend working up a load with each, shooting over a chronograph and seeing which primer/powder combo works best. Get 100 of each to start.
My best 7mm Rem Mag load consists of the 162gr A-max, 70.2gr of RL22 and a Fed 9 1/2 primer (not magnum) in a Norma brass. It's not very hot in my 24" barrel and averages almost exactly 3000fps, but it is very consistent/accurate. This is above some listed loadings, the Norma brass I have seem to have a larger internal capacity than other brass I've used, and thus I usually end up with more powder for the same velocity than the books show (still with no pressure signs). So PLEASE work up your own load in your own rifle/brass etc.
