My buddy, whose younger eyes are a lot better than mine shoots inside of 3 inch groups with the flintlocks he builds himself, patched round balls and iron sights. Scoped as it is, my Huntsman will shoot inside 3 inches all day with heavy cast bullets. I find sabots go every which way at 50 yards, let alone 100. I also find mine shoots better with a fouled barrel than a clean.
I might add, my buddy Wayne, is a member of Treasure Coast Muzzleloaders in Florida. I used to belong and got their news letter for a number of years. Wayne invariably wins all their matches. He'll be here on the 14th for our deer season; bringing up a new flinter. He's built .36, .45, .50, .54, .56, .62' .69 and .72 calibers. I was with him when he shot a 7 point at 90 yards with the .69, 1 in 96 twist, and a patched round ball with 140 gr. ffg behind it. The deer went over like a silhouette target.