Ramshot's data lists 20.7 grains with the 20 Hornady V-Max for 4057 fps from a 24" barrel. I tried various charges up to that to see what shot best, but as I recall was using anywhere from 19.5 to 20.5 grains, depending on the primer and bullet.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
