Most of the blackpowder shooters I know and shoot with load a hard card over the powder and some put about a 1/4" felt wad on top of that. Then the shot is poured in and a thin card put on top. Circle Fly is a source of all the wads you need. Plastic wads do make a mess with blackpowder's heat. If you want to try concentrating the shot experiment with heavy paper wrap on top of the fiber wad surrounding the shot like a plastic shot cup.