I am relatively new to reloading for the 300 Win Mag but have found that Retumbo works best with 200 grain Partition bullets in mine which is a Win Model 70 Classic SS with 24" barrel. Great accurracy and top end velocity. I stopped short of Hodgdon manual max loads since I was getting just under 3000 fps. I shot mine from 100 to 500 yards and accuracy was better than RL 22 or H 4831 sc. Don't know about lighter weight bullets though. Shot loads in temperatures from 80 degrees F to 20 degrees F with no changes in POI.
