1. Buy some plastic sabots for the bullet diameter you intend to use.
2. Buy handgun bullets in your selected diameter.
3. Load it over the Pioneer powder (I use the stick form) Jim Shockey pushes. For once, this is a product that works as advertised; i.e., no muss, no fuss and very little fouling. You can shoot bunches of time without having to clean the barrel unlike other products.
4. Another option is to buy the muzzle loader bullet/sabot combo packs put out by a number of manufacturers.