With the 165 grain cup and core bullets you will need a powder a little slower than those shooting the 180s. I found the best results with IMR4350,but I will let you find your own sweet spot because the 300WSM seems to like higher operating pressures. My good friend has an A-bolt hunter in this caliber and it is a real tack driver with 165 grain Hornady SST bullets with IMR4350. BTW, he has killed at least two elk with this load and they were bang/flop shots, although we all know that is impossible because these Hornadys are not "premium bullets".LOL