Nothing new under the sun. Match shooters did that for years with brechloading BP firearms. One case, reprimed for every shot. Prime the case, load with BP, and seat a wad over the powder. Load the case, then seat a bullet downbore onto the case. Consistent charge, consistent seating, shows up on target. NOT muzzleloading, anyway you look at it.

I guess I'm just funny, but I thought the whole idea of muzzleloading was to use a muzzleloader and BP...