The rule of thumb is to develop your Ball (spherical) powder loads with magnum primers because it's harder to ignite than flake or stick powders. Standard primers will work, but can give you erratic results sometimes, which equates to groups larger than the rifle's true potential.
I know there will be someone who disagrees with this because their reloading manual uses standard primers, but this is what I use, and it is common knowledge in the reloading world.
NCsmitty