RE: 300 rum handloads
The most dynamic load I have found is 94gr of H1000, 180gr accubond or partitionand 215M primer loaded to 3.6" COL. I have gave this load to several and it seems to shoot very consistently. Bad news is all you can expect is 3150 to 3200fps.
I can't recall my load, but with 150gr BT, I used IMR4350 and got outstanding results. But I think I only got 3400fps velocity.
Another load that worked out real well was 89-90gr of RL25 and 180gr TSX. Real accurate.
A good long range target load is 95gr of Retumbo and 190gr matchking.