H110, 21 grains. Should be good for 1570 fps give or take the tolerance differences between our rifles. The 44 would be a great cartridge to begin handloding with. There area a number of powders that will work well. H110 will give about the best velocity in most cases, but I have found AA1680 to give be very accurate although it is slower by 150-200 fps or so. 2400 works well, 296, Blue Dot, the list is long. Everybody that makes bullets, jacketed or cast makes 44 bullets. Brass life is good, once again, if a brass maker makes anything, the lineup will likely include 44 brass.
As a side note, I have found my most accurate cast loads to occur between 1200 and 1300 fps. With jacketed, the rifle will shoot 1 to 1.5" groups to the velocity limits of the Mag. Stay in touch!
