I've never done real black with coated boolits, but from everything I've read, it's not a good combo.
I don't know of anybody doing 45 Colt Big Loob's for sale, so what I do is just load up the cartridges with real black and seat a soft lead boolit on top, then after loading, smear some loob (Bore Butter works, except when it's warm to hot, it becomes too liquidy) over the front of the cylinder chambers. Then run a brush through the barrel after shooting the stage.