At temp do you think the magnum primer would work in which a standadrd primer wouldnt. Ive used the BR2 primers in single digits with no issues but that was also in conjunction with a smaller powder charge and case in a 6.5x55
Increasing primer brisance basically always improves temp stability on the low temp side, since the problem is fundamentally getting the powder lit.
Depending on the load lower brisance primer can work fine, but if I have to pick one that's not the direction I'm going to go for a hunting load.
