I think it is possible that a flatter shooting round might require a higher front sight when an aperture rear sight is installed, as the flatter shooting round stays closer to the bore line. Thus a high mounted rear sight will result in a bullet strike much higher than lower one. The open rear sight is mounted on the barrel, and the top of the receiver is somewhat higher than the top of the barrel, although the open sight is visible to the shooter looking actross the top of the receiver. The receiver sight though is mounted above the receiver, and a gallows style receiver sight, such as the offerings from Lyman and Williams, has an aperture well above the height of the receiver, suggesting that the very lowest position of the receiver sight will still be quite a bit higher than the highest position of the open sight. Now any given front sight height will work within the tolerance of normal sight adjustments, but not when you double the height of the rear sight, and still expect to hit point of aim at a 100 yard target. The situation is also affected by the distance between the sights and the barrel contour, where a long non-tapered barrel, such as the octagon barrel found on some commemoratives has the front sight dove tailed into the barrel, does not require as high a sight as a short carbine with a light contour barrel, which typically has the front sight dovetailed in a sight base which is attached to the barrel.
