The gunsmith made the mold with a "cherry" bit, to fit the bore, expecting a patch. We know this from surviving molds, cherries and rifles. We also know that trading posts and armories sold or issued pre-molded ball as inventories mention "rifle ball" as well as "musket ball" and "carbine ball". Whether the ball was a good fit for what was locally used for a patch in the rifle, or not, is not known. Not every rifle today is a "good shooter" and it's possible that such was the case with barrels back then, until or if ever the owner got a proper patch to go with the ball. Look at the numbers of posts with fellows having accuracy problems today with modern barrels made by using machines that have exact tolerances. Some folks today have to put a buffer between the powder, and the patched the ball to get the barrel to work, right?
LD