Since you're looking for some extreme range shooting I would suggest getting a very good quality rifle. Look at the Knight, Thompson Centers, CVA, Traditions and H&R and other brands, top of the line guns. Many of them are going to be expensive. Your also going to want something with a longer barrel because of the distances you want to shoot.

There are many rifles that will get you into the black powder sport and they are reasonable. If you practice with almost any of them and find the right load, they will shoot well.

It will take a lot of practice to be able to shoot 200 yards with any muzzleloader. Shooting from the bench rest at the local rod and gun club is a lot different then leaning into a tree out in the back 40. So find a good load and practice.....