CW, thank you for the very clear answer...My main concern is that everyone knows the difference between the muzzle loader rifle, which needs a patched ball, and a mortar, which needs to have the windage to prevent build-up of dangerous back pressure.
And A. Roads, thank you for the info about the filler and the cardboard disk. We all like using less powder to get better results! Ya can learn something new just about every day on this forum! BoomLover