Wow, 10" at 25 yards. There is something seriously wrong here. A problem like this, I wouldn't bandade by shimming, or grinding or whatever. I would find the root of the problem.

I have had trouble out of cheap simmons and even burris signaturelike this. Thats the reason I buy leupold scopes. Lots of adjustment. What kinda scope is it? I know you said it was leupold bases and rings, but not the scope.