To be honest, 155gr bullets are a bit light for the 300WM, the velocity is impressive, but, it peaters out quickly.
Powders like 4350, 4831 & H1000 will serve your needs.
My favourite load with 150gr Nosler BT's was 76gr of H4350. This is a max load, but, my rifle was long throated.
Cheers.
gun)
Thanks for the info. What velocities where you getting with the H4350 load?
Most people here run heavy-for-caliber bullets in their rifles.
I shoot Berger 210 VLD's in mine, backed by 7828 SSC powder. From what I have read, the Berger 215 Hybrids are most people's favorite for the .300 WinMag for both target and hunting.
Every rifle is different, so you will need to work up your own load, using someone else's data is rarely relevant for multiple rifles.
Light for caliber bullets are fun. I've got a 30" 300RUM and it's a 13 twist. I cook the 168 tipped sierra matchkings @3580 fps. With a .545 b.c. it's a flat shooting almost no recoil gun. I really like it. Barrel life isn't much but worth it
Currently, I am running 185 bergers. They group great, but for deer and other midwest sized critters I'm thinking the 155s might be better suited. So, I'll try them and if they don't perform like I hope, I'll stick with the 185s.