In my native CO, muzzleloaders used in the muzzleloading season must wear open sights and scopes are not allowed. But you can use a scoped muzzleloader in the regular rifle season. When I was stationed on the East Coast there were a lot of areas where you couldn't use a centerfire rifle. It was archery, shotgun or muzzleloader and the muzzleloader could be scoped. That's why I have a Rem Model 700 ML in 54 with a scope. It smacked a lot of whitetails in VA.