When I lived down south I would use magnum primers in the cold, when the powder charge exceeded 50 grs, and when I loaded ball powder. To resolve the logistics problems involved with living in the north, I use magnum primers for everything, even for cast bullet loads, the exception to this being match primers for my target rifle. I have suffered no loss of accuracy in my hunting rifles as a result of this practice, and even if I was to move back to the land of stores and gun shops, I doubt that I would go back to standard primers.