LonesomePigeon,
I've been casting and shooting PRS Big Lube bullets with black powder for quite a while now. They carry enough lube to keep a rifle barrel from fouling out. So they're famous for being able to maintain accuracy throughout a match. But although they deliver adequate accuracy at CAS distances, they quickly lose accuracy at 100 yards and beyond (no surprise--PRS Big Lube admits as much). And they haven't helped me in avoiding foul-out with revolvers. I put about 20 of them through my Standard, loaded with 35 gr. 3f Olde 'E', and the hand still began having difficulty rotating the cylinder at that point.
I don't think they'll be your "magic bullet" for keeping your revolvers running any longer with BP, sorry to say. They certainly have their place in allowing long strings of fairly accurate rifle fire, but that lube doesn't seem to help keep a revolver's cylinder from binding up, at least in my experience.