If you use about 80 grains of 3F and a over powder card wad, nothing for projectile and compress the powder fairly heavily, it should make a pretty good bang and still have low pressure. No crimp and no cream of wheat etc just powder and a card wad. If you are using any sort of material in the space where the shot goes, cut back to 2F. If the powder is not compressed enough, you will no get the bang
Don't forget to wash the barrels out afterwards
cheers mooncoon