losthwy, how are you patterning your guns, off a bench like a rifle or are you just mounting and shooting? Either way it can be fixed, you may want to look at an add on rib, or have the gun fitted to you. A gun that shoots high can generally be cured by making a change in the stock dimensions, by increasing the drop (pretty difficult to do unless you shim the stock), or by changing the pitch of the stock (the angle of the recoil pad). If you are a stocky built individual you may want to start with adding a shim in front of the recoil pad that is thicker at the top than the bottom to accomplish the necessary pitch change. There are a lot of variable's here and it would be a good idea to see a stock fitter and get their take on it. One other question, it would be my guess that with the Winchester mounted you see alot more of the top of the rib than on the Beretta (like if you are looking down a flat road standing up, versus squatting down), is that true? If so then it may well be the gun fit, if not you need to try and make sure your chokes are concentric (this can be corrected but you'd have to have Briley or someone make some custom chokes to fix it), or you can look for the add on ribs (such as the "Adjust-A-Rib System" @
www.ncp.com) and that should take care of your problem.
Gordon