Both of the all-in-one kits above include three of these speed loaders, but I like to have a couple of additional ones on hand. This particular speed loader can hold up to 140 grains of loose or pelletized black powder and has a volumetric marking system on the side.
Black powder guns are a whole different ball game compared to shooting standard firearms, but are still used for sport, reenactment, and enthusiast shooting. Cheaper Than Dirt! has the supplies that you need to get started in black powder shooting, including powder, patches, wads, and projectiles.