Williams open sights

[cluck]

In need of some information on how many left/right or elevation marks would I move the sight to move the center of the pattern six inches? Or put another way, how much does moving the sight one Mark move the center of pattern? This is for a forty yard shot. Seems like every time I change to a different shell or choke it shoots to a different poa at forty yards. Many thanks for any information.    Cluck