I have gotten my best accuracy out of 64.5 grains of IMR 4831 with 150 grain Nosler Ballistic Tips. Less than 1" @ 100 and 3" at 200. I get similar results with 60.5 grains of IMR 4064. The only other powder I have tried for my .300 WSM is Winchester 760 and it didn't perform as well as the others mentioned. Also, I'm shooting a Tikka T3.