Hello and welcome to the forum! You will get many answers over this oft asked question. Using a patched round ball, typically out to 150 yards for a rifled barrel, one can produce very good groups. For a smooth bore, about fifty yards. Much of it depends on the individual's ability, the correct patch/ball combination, lube used, cleaning between shots (or not), how well the barrel is made, will all be factors. The larger the caliber, the less wind will affect its flight.