I haven't reloaded for my 300WSM in many years...my rifle doesn't like factory loads and most tend to be way too hot. My reloads hover around the upper end of 30-06 velocities with 165 Interbonds. I used H4350. It remains one of the top of my go-to powders.
I see a lot of people singing the praises of Reloader 17 and the 300WSM.
I've used Reloader 22 and it works great! That said, I'm using Reloader 17 lately. I've had success with H4350, Ramshot Hunter and H414. They all work fine and the loading manuals most likely have more suggestions. I try to buy big jugs of powder and don't experiment as much as I used to. My wife was diagnosed with twins almost nine years ago and the condition appears to be terminal. If you need tips about Cub Scouts, Flag Football, 3rd grade homework, Piano classes or birthday party tips I can help.