I have found more consistency with non mag primers, as far as shooting a mile, I am not going to pretend I know anything, I have no clue what it takes to accomplish this, I am going to to stick to what I know, which is 5 MOA bullet drop after that I have no interest, so basically 600 yards which is 1/3 of what you want to accomplish, I would not be surprised if the same approach applied but I cannot confirm that.

Dean