I've had good luck with H4831 in three .280 AI's, but along with RL-26 am also going to try IMR7977 in my latest, since it also looks to be just enough slower than 4831 to possibly work very well. Like 26, 7977 is double-based so should provide a little more zip.

“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck