RE: 300 RUM
Well, a good reliable load (but slow) is 94gr of H1000 and 180gr accubond with 215 primers. But you will only get 3200fps most likely.
Another good one is 95gr of Retumbo and 190gr matchking. Lots of muzzleflash for some reason.
Another favorite of mine is if I can remember 89-90gr of RL25 and 180gr TSX.
All are loaded to 3.65" give or take.