I use 24ga. plastic shotgun (they come primed) shells cut to length and loaded with BP and usually a .590-.595 round ball over some tissue wadding. They shoot to my carbine sights closer, but still high, than the big conical (I think the load and sights were regulated to make man (vertical target) hits to 200yds..
The shotshells are easy to load and I get 3-4 reloads before the primer pocket get kinda loose. The brass cases and dieset are way expensive and the dieset requires bigger threads than most reload presses have. Usually with brass for my single shots I dont resize after first getting and prepping the brass unless it gets sticky extracting from the chamber so going with brass and dies didnt make any money sense to me.