I shoot mostly 300 grainers; Parts, I Lock's and Hornady solids. 78grs. H4350 works for me. Another 2 grains of the same for 270 Hornadys. Each use WW cases and Fed. 215's. Speeds are 2,500 and change for 300's and 270's are slightly under 2,700 from a 24 in bbl..

H414/W760 is supposed to be a great powder too; never used it in 375 HH.

Hope you njoy the 375!