You may have a problem with the -0.010/+0.010 inserts installed but if you are that close and find that the Highs don't quite work, I would not go up to the extra highs as they are just too high. The actual spacing from base to bottom of the scope tube for the three 30mm sizes that Burris offers in the Signature rings are:
Ex High 0.58"
As you can see they mean it when they say Ex High.
I use the Mediums with a 20 MOA rail and the Highs with normal bases like on a Savage. My scopes are big tactical styles with bells about 2.2 inches across (which is actually bigger than the 50 mm they say they are).