Nothing...... Sometimes, depending on range, you can have significant dirft on your shot when using black powder is all. You don't have this if you are using standard jacket loads typically, or way less I should say, but if you are like me and you enjoy Muzzleloaders, then you kinda have to be a good judge of distance and windage. You figure, and some people will argue this point, but 200 yards is about the best you are going to see from a Muzzleloader. The closer you get, the better the shot obviously but sometimes your stuck in the inbetween, so to speak. At 100 yards, you basically have a little over 2 inches of drop off, in perfect conditions, depending on the load etc. Velocity is a key factor here and so, you really have to understand the role of Gravity because its very pronounced according to how far out you take the shot. Figure another inch at 150 yards and maybe 9 to 10 inches at 200, just depending. Factor in wind and it becomes very challenging indeed. At 200 yards with a 10 mph wind, you figure maybe 10 inches drift, give or take. Anything further out then that, the numbers start getting a little difficult. Ideally, you are shooting for a 6 inch zone so all these things must factor into your shot with a Muzzleloader. Never mind that the wind changes direction, never mind that you must be able to judge angels, never mind that the further out you are, the harder it is to know if the wind is consistent all the way to target and we haven't even started talking about temperature variations and how that effects loads.
In short, I recommend you try and get to a point, as close to 100 yards as possible, when using a Muzzleloader. If you can do this, then them Clowns are no trouble at all. Now, getting them mounted, thats a whole nuther discussion right there.
;-)