I have not used IMR 7828 in any of the .30's. But I find it to be excellent in the 7mm Remington Magnum, for which I understand it was specifically developed. It is slower than RE22, so if you have to use a compressed load of RE22 in the .300 Win. Mag. to get opimum performance, it is just possible that the case won't hold enough IMR 7828 to do the job. It might be outstanding in the .300 Weatherby for heavy bullets, however!