I always figured that LR Mag primers were suitable for cartridges like the 7 mm mag but, while shooting the breeze with a friend He mentioned that he called several companies, Sierra, Federal, Hornady with some question and was told by all of them that charges over 80 grains required Mag primers and anything less than 80 didn't. Think I will try stnd. primers in my 7 mag. and see what difference it makes.