hanshi - years ago when I had the .44 smoothbore, I experimented with non-patched round balls, ie: card behind and card in front, but the accuracy I received was much inferior to that with a cloth (denim) patch. With a patch, that little smooth rifle would stay on a hare's head. Without patch, the accuracy was closer to 8".
James is correct in that most smoothbores weren't patched - as least those I've read about. They were usually military guns or guns of military calibre that could and did use the paper ctgs. issued to the mil. Loading bare bal on top of powder, no patching nor wading at all was common when running buffalo - the ball was spit into the bore and muzzle kept up until the shot was made, drop the muzzle and pull the trigger, so the gun went off before the ball had a chance to move - well documented in Firearms of the American West. What patch or wad was loaded with ball in the double barrel shotguns that became popular on the frontier in the 1830's or so, I don't know- not described.