Often I don't use a muzzle loader, but when I do, it's a sort-of traditional Thompson-Center White Mountain Carbine. Neat little short version of their Renegade cap-lock .50 cal rifle. Really a nice handling little carbine/rifle.
Over the years I've used both black and pyrodex powder. My best results on game - mule deer - have been with 385 grain Hornady hollow point "Great Plains" soft lead bullets. I don't even belt 'em out all that hard, 80 or 90 grains. Only shot two mulies with these bullets, but in both cases the deer died instantly, or nearly so, leaving me with no tracking. Also the bullets each penetrated completely, which actually surprised me since the bullets are such soft lead with large hollow points.
Effective range on this stubby combo? I practice until I can place all my shots on a standard paper plate, from standing. Usually I max out at around 75 - 100 yards. Both the mulies I shot were within 75 yards. I like the challenge of getting close. If I want to shoot far, I use my scoped modern rifles.
Regards, Guy