My Accura shoots good with whatever I put down the bore. I've used real BP, Pyrodex RS, BH209 and Alliant Black MZ. I am really liking the results I'm getting from the Black MZ. It burns as clean as BH209, you don't need a special breech plug and you get higher velocities at lower pressures. And it works in percussion cap sidelocks as well.
But each ML is a beast unto itself and you need to play with it to find what it likes. If you're near a Sportsman's Warehouse grab yourself a bottle of Black MZ and try it. Or Walmart carries Pyrodex RS.