I do not load the .44mag, but the .44-40, with cast bullets from 200 to 310gr.
Under 240gr, I get my best results, both accuracy and velocity, with IMR4227.
I am using up to 26gr with a 240gr swc with gas check and getting 1650fps with a '92 carbine, no case expansion at the base, I mike every case after firing it.
For the 310 rfn gas check, I am using 19gr H110 and getting1350fps, interestingly enough, the same load with the 240gr gives only 1200fps.
Accuracy was about 3" at 50 yds until I sluged the barrel and found it was .429, not .427, can't chamber loads with .429 bullets, so made the front end .429 and the portion in the case .427, brought the groups down to less than 2" at 50yds, good enough for the deep woods and brush I hunt, 50 yds is about usual range.