That is the beauty of the reflex style of sight. The dot is a reflection on the glass. you do not have to have the dot centered in the window for it to be on target. if you can see the dot and the dot is on the target it is aimed at the target. Even if the dot is in the corner of the window. So this gives you the ability to move your head around or shoot at odd angles and still shoot accurately. This is one of the reasons why the sight is so fast, no lining anything up. Put the dot on the target and pull the trigger. Dont worry if the dot is in the center of the window or not.
This confuses people till they see it for themselves. Put the gun on sand bags and put the dot on a target. Without moving the gun, move your head around. The dot will move around on the glass but will stay fixed on the target regardless of where it is located in the window.
Now the real magic starts when you shoot this sight with both eyes open. leave both eyes open and focus on the target not the dot. When you do this, the dot leaves the sight and appears to be floating out there in space with the target. Takes a little practice but it really makes the sight fast and enables you to hit fast moving targets like doves or clay targets.
