Any number of muzzleloaders will shoot tight groups at 200 yards. Also, a round-ball rifle can be as accurate as any other kind. However, the round ball loses velocity so fast that it has a very steep trajectory beyond 50 yards or so. Additionaly, the RB is greatly effected by crosswinds, so shooring at distances much beyond 100 yards is very chancy if any wind is blowing at all! Consequently, if you want to shoot at longer ranges, you will have to use a bullet with much higher ballistic coefficient than a round ball has. This means using a barrel with a much faster twist, to stabilize the long bullets. Such barrels cannot be used accurately with round balls, except with very light charges. Otherwise, the balls strip, and accuracy is lost. You will need at least two guns (or interchangeable barrels) if you are going to shoot long, pointed bullets and round balls both.

Keep yore powder dry!!