The best powder I have used in the 300 WSM so far is VV N550. It is a "high energy" powder and gives excellent results with the 165gr bullets I load. It costs a bit more than some powders but no more than I shoot, I feel its worth it. Another that really shines is Alliant RL19. This was the first powder I loaded in my WSM and gave excellent results as well. With the 180 gr bullets you plan to use, You could do no wrong with either of these, as well as RL22, and VV N560, the two next slower powders for each company.