Not all guns have two beads, Bob. If they do, they should be placed one behind the other. Then you shouldn't see any rib. If they don't have two beads, you should still be looking straight down the rib so that your eye is in plane behind the rib and the bead should be on (or leading) the target. If you look down on the rib and can see the whole rib, then the gun is going to shoot higher than it is supposed to and the shooter is going to have to caculate the distance of the bird/target, how low to hold/shoot under the bird to calculate for this plus how much of a lead to have on the target. Much easier to just look down the rib, and calculate the lead than doing both. Or look at it this way, when you shoot a handgun, are the top of both sights (front and rear) level? Or do you raise the front sight so that it is higher than the back one? What's going to happen? It is going to shoot high. Unless you are shooting long range and walking the bullets out to the target, you aren't going to shoot that way are you?