Yes, a rifle scope works just fine. A muzzleloader is a rifle and more then able to shoot long distances. If you were to have the same scope on a 30-30 or 30-06 would you feel like you were over scoped? Variable scopes are able to be turned down so that they can work at shorter distances and longer distance. The thing you might encounter is the longer parallax might give you a less then clear picture at very close ranges. I use rifle scopes on three different inline rifles with no problems at all.

The big thing for me is eye relief. I like to have 3.7 - 4.0 inches of eye relief.