Beowolf, you do know when loading cartridge cases with black powder you can't have left over space in the cases after seating the bullets, don't you? In fact I, and most other black powder cartridge shooters I know of like the black powder charges slightly compressed.
How would anyone here know whether or not 25 grains of the black powder you want to use would fill your .44 Magnum cases enough to where you'll have no left over air space in your cases once your bullets are seated? I could go down in my basement to my loading bench and give 25 grains of black powder a try in a .44 Magnum case, but then I have no idea what granulation of the black powder you want to use is, nor do I know how far into your cases you want to push your 180 grain "balls?"
Okay, now let's here from all the "black powder is measured by volume, smokeless powder is measured by weight" gurus. Yeah, I know that. It still takes a specific weight of a specific granulation of black powder to fill a cartridge case to a specific volume. And with black powder, or black powder replicas, you don't want left over space in that case once your bullet is seated.