I personally don't use a scope on my muzzleloader. The only reason is a friend made it for me and it will not take a scope. Matter of fact the sights he put on it, I had to use a file to sight it in. lol He was an old guy who liked the old ways. He died a year after he made it for me and it's kind of silly but I kept it the way he made it as a sortof tribute to him. I still use round balls and triple F blackpowder. But still the gun is acurate out to 100 - 125 yards and where I hunt thats about all the range you need. But I don't see any problem with scopes on em if you want one.
We cannot continue to do the same things and expect different results