IMR 7828 seems to be THE powder for the .300 Weatherby when using 180 grain bullets. In my .300 Wby Sako I've used several 180 gr. bullets, including the two you mentioned, and IMR 7828 just seems to work with everything. That's not to say that other powders won't work too, but 7828 gives me the best accuracy and velocity on a consistent basis with 180 gr. bullets.

Here's a favorite load:

84 grs. IMR 7828
Fed 215M primer
Norma brass
180 gr. Swift Scirocco
OAL - as long as the magazine will allow, about 3.65"

Recently, however I've started using the 168 gr. Barnes Triple Shock almost exlusively because I like the bullet construction better and I've had good luck with RL22 as well as 7828. 84 grs. of RL22 gives me about 3340 fps and accuracy is very good.