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.
Retumbo is another Hodgdon Extreme powder, and works very well with heavy bullets in the .300 magnums from the Winchester on up. Another one to try is H1000, which might give better accuracy in some rifles, especially with 180's.
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