I'd personally try the 200 grain accubonds. H4831SC and RL22. In fact, I found 71 grains of both powders to be very accurate. Of course, I have a custom 300WM built on a win M70 action and I have a .375 H&H magazine box and follower so my OAL can be as long as 3.58". You may have to start out lighter and work up when seating shorter. Also try 180 grain accubonds or partitions with 74 to 76 grains RL22.