Same have been using R22 for awhile. Next loads will be with R16 & R26. as I haven't tried 150s in the 300 so doing so now for grins. R26 usually has the highest or in the top three highest for velocity from 150s to 215s.

DF RE: H4831 it might be as JB and others have written that for some reason a faster powder obdurates better with Partitions. They need an extra kick in the pants sometimes to do their best accuracy wise.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli