After a fair amount of experimentation my favorite 300WSM loads include 165 grain (Accubond or Partitions) or 168 grain (Sierra Matchking or Nosler Custom Competition) bullets with 60 grains of H380.  These have proven to be very accurate loads for me.  I tried lighter 150 grain bullets but they were not accurate at all.  I'm firing these rounds out of a Browning A-Bolt Stainless Stalker.  I've been very very pleased with the performance of both the rifle and these loads.  Using the match grade bullets from the bench I frequently get 3-shot groups that are one ragged hole; the hunting bullets are usually under an inch at 100 yards with 1/2" to 3/4" groups not uncommon.  The rifle is out of the box but I have the trigger adjusted to the lowest possible trigger-pull setting (A-Bolts have adjustable triggers, no gunsmith required).  Good luck.