I was given almost 1000 LRM magnuum primers. They are winchester brand. There is 10 packs nwith about half of 1 pack gone. I don't use mag. primers in any of my rifle loads. I reload 30-06 ,308, 270 win., 243 win., 30 remington , 7.62x54R , and 7.63x39. How much do you have to cut back on powder charges to use a magnuum primer. The shooting here in louisiana never gets that cold. Maybe in the teens but not often. I use in most all reloads IMR powders. 4350,4895,3031 mostly those three . I use cci LRP primers in all but the 30 remington. In it I use remington 91/2.
Zacharoo