O.K. Here we go one more time. Throw the patch away, and shoot an undersized bare ball, with a big powder charge, and a wad of greased wool blanket on top, to keep it in place. It will shoot fine in a choked bore.
But, choked bores only existed on the very edge of the cartridge era, so why use them? If you quit loading your smoothbore like your building a modern shot shell in the bottom of your barrel, you can get tolerable shot pattern out to about 30-35 yards. It’ll take time, patients, and practice, because not all smoothbores perform well with the same load.
Hungry Horse