I have some Sierra 140 grain bullets and some 150 grain Nosler bullets I plan on loading later for my 7MM Rem. Mag. Can I use large rifle primers to load with Hodgdon Hybrid 100 or IMR 4350 powder?
You can use standard LR primers for the 7 mag without to much problems, unless your hunting in sub zero temps, I wouldn't worry about it to much. A mag primer might also boost your velocity 25-50fps, but again, not really a significant difference.
7 mag dont really burn that much powder to actually NEED a magnum primer.
Have to admit to using Fed 215 mags though in mine, but thats just because I started with them and haven't ever changed.
If all I had was some Fed 210's or whatever, and they shot good, I wouldn't see a need to change them either.