Under no circumstances use plastic modern shotshell wads. They are not designed to take the heat from the BP, and they will leave a mess inside the barrel that is dang tough to get out. I use tow, or news paper. In fact I make paper cartridges to hold the powder, tear, pour, and simply ram down the empty cartridge tube on top to form the wad. I then load a second cartridge that holds only shot, only I don't tear it open, I simply load it as is, and seat it on the previously formed wad. Works like a charm.
LD