Go to the Alliant web site for their load data for the 300WSM using RL-17. I am loading my Ruger 77 Mark in 300 WSM
with RL-17 and 168 grain Barnes TTSX bullets. Alliant list 68 grains as their max with a 165 grain Speer bullets. I am getting just a little over 3000 ft/sec with 64.7 grains in WW cases and 215 Federal primers.
My Ruger has a 22 inch barrel. I have shot 168 grain Berger out of my Winchester 70 Coyote in 300WSM which has a 24 inch barrel. I did not match the velocity that Alliant shows on their web site for 68 grains but 68 gains did give me over 3100 ft/sec.