tealboy

I had a Benelux montrofeltro that when I first shot it, was missing all clays. Learned the shims in the box were to adjust the drop and butt. I really didn't know what I was doing but put diff shims until I was on. Can I accurately measure the setting and apply this to a new gun purchase? My intent is to order a new over under online but having remembered this experience, don't want one that doesn't fit unless over understand can be adj similarly to my benelli. I see silver pigeons have certain comb and heel drops whereas cz and browning have another. How can I make sure I get the right one? If I could match to my benelli might be perfect but not sure how to get this right. If the benelli wasn't adjustable I down a gun that I couldn't shoot so don't want that to happen.