This is what I meant. One can aim with a piece of post-it in the middle of the screen.
If you are sighting along a parallel line to the guns. Of course a dot in the center of the screen will be close to where the guns hit.
That is exactly the same as putting a dot in the center of your glasses.
As long as you are looking the same direction as the gun you are holding. You will hit where the dot is, except for the distance offset between your glasses and the gun you are holding.
No way to prevent this, unless you wish to not look straight ahead in the plane?
HiTech