I haven't loaded for the 300 WM, but I have for other calibres. I use IMR4350 in my Swedes. H4895, BLC-2 and Varget in my 308's. I have read good things about H1000, H4831 and H4831sc (short cut). Adding to what sunray said, you will have to try different combos to see what powder, bullet combo hold most promise. Then you'll have your load to fine tune.