I have been shooting and loading for the 300 wby for longer than I care to remember. I load for a lot of guns other than mine, also. I have been shooting 210 -220 class bullets for the last 15 years. My combo....
Reloader 22 for 180-200 grain bullets, reloader 25 for 210 - 220 bullets.
Fed 215 primers.
I have tryed many, many powders in both my match guns and hunting guns.
It always ended up being RL22 untill the RL 25 came out. That is when I started using both, depending on bullet weight.
Retumbo came in a close second. Other powders I have tried....H 4350, imr 4350, h4831, imr4831, h1000, imr7828, h5010, bmg, h414.......hell I can't remember them all. i would like to try some of the Vihtavuori powders.
All of my hunting and match bbls shoot berger 210vld's/RL25 into itty bitty holes. I do have one match bbl that never made the cut as a match bbl now shooting 210 bergers to 3270 with Retumbo for a LR hunting BBL!!! SMOKIN!!!