Full length size your cases and run them through the rifle before you load them to be sure they are sized enough. Don't load hot! I haven't loaded 165 grain bullets for my 300 Savage rifles. I use WW-748 for 150 and 180 grain bullets. The 300 Savage case is limited in capacity by the short neck and 2.6" overall length of the action.
Ffor 150 grain bullets, use 40 grains of either IMR 4895 or 4064, or 42 grains of WW-748. I use 41 grains of WW-748 with 180 grain round nose bullets. I have recently been using CFE223 and LEVERevolution powders in my 300 Savage loads and those powders work well.
For 165s I would split the difference in powder charges between the loads for 150s and 180s.
