.44 Special and .44 Mag have what is, for practical purposes, the same maximum COL, and pretty much, if you use the same COLs, .44 Special loads will perform about the same in a .44 Mag case. Some makers may thicken the .44 Mag brass case heads a little, reducing capacity a little, but the .44 Mag would tolerate the slightly higher pressures that would result very easily.
Try 4 grains of Red Dot for a target load. 5 grains will give you a plinker with a little more oomph.
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Patron Member