I shoot a 300 Rum .
Federal 215 Match primer.
Retumbo powder . 85.5 grains.
That is the starting load on the berger chart I am getting 3050 FPS verified by my exbal real world drops.
Remington Brass (make sure you stick with the remington brass . I used the Nosler custom and had pressure problems with it. I was told by some forum members that it is alot softer than the remmy
I get very good groups with the retunbo powder but I am going to try the 215's next