Green Dot is what I've used for many years with my own cast boolits in .44 mag cases. That was after I had discussed it's use in the .44 mag with an Alliant(formerly Hercules) tech rep. He told me that "Green Dot is one of the best kept secrets in loading for the .44 mag". Of course we were talking loads in the 700 to 1100fps range, not magnum loads. Take any load listed for Unique, and drop it by approximately 1grain, and use Green Dot. The velocity will be very very close to the same, accuracy will be the same, but you will use less powder and thus it will be cheaper to load. During powder shortages that we have all experienced lately, Green Dot was always available here in the Pacific Northwest.
I load on a Dillon Square Deal B, and it's powder measure throws charges of Green Dot that are no more that .1g +-. YMMV.