I have not seen many muzzle loaders that will not shoot well at 100 yards, even the older slower twist sidelock ones. As long as you find the right load and load it consistantly it should shoot as well as you can. I had an old CVA kit when I was kid that my dad and I built and I could kill woodchucks at 100 yards with open sights.

For a modern inline 100 yards should not be much of a challenge really. The accuracy you are describing sounds more like a smooth bore shotgun shooting slugs. I think bad accuracy out of a modern inline at 100 yards would be 3 inch groups off from a bench. That is with a scope by the way. My remington will shoot between 1-1.5 inch groups pretty consistantly, and the majority of the time I can get three shots into one ragged hole. When you extend your range to 150-200 yards things get a bit more complicated though.

The savage is an excellent gun, you should have no trouble getting good accuracy out of it.

Paul