So there is no reference so far known that shows patching of round ball in a smoothbore in the 18th century. YET riflemen and patched ball were known both in the American Colonies, and in Germany.
There are references to Select Marksmen using round ball in a smoothbore, but they did not use patching.
There could be a lot of reasons for this, both in the civilian and military world.
One theory is that when you patch without rifling present, the patching folds differently each time, while when there are rifling grooves the folds happen in the grooves the same way, AND of course the patching imparts the stabilizing spin.
Another theory is that while rifles were often sold with a mold, so that the buyer would have a ball close to the bore size, and thus could load with a tight, or slightly less than tight patch as the shooter chose...,
Smoothbore shooters often obtained pre-made ball, or in military formations, a few molds were provided for the entire group of men. This meant that the ball was likely a lot looser than the difference between a rifle's ball and barrel size. SO..., while the rifleman with a .54 was dealing with a self molded ball of .530 or .520 size, the smoothbore guy might be dealing with a .590 ball in his .62 fusil or .65 carbine, or a .690 ball in his .75 Bess.
So for the 18th century smoothbore shooter, perhaps patching didn't work, as they didn't have the option of going to a bare .610 or .615 with a patch in their .62 fusil, or a .730 ball with a patch in a .75.
The Select Marksmen of the 18th century would be issued ball..., and then would roll paper cartridges for accuracy. I think they were making custom sized cartridges that fit just so in their bores, each man knowing exactly what his musket liked when it came to getting an accurate shot out to 90 yards, while using that issued ball. It's also known that only a small portion of the Select Marksman's ammo was thus made, and that the rest of his ammo was standard military rounds. Likely because after a few shots, his bore was so well fouled, that he had to resort to the standard ammo, and save any remaining "accurate" loads until he could take a break and swab his bore, similar to a rifleman.
LD