Thanks again for responding Mad Dog and Jonbearman. It is nice to get others involved to solve this problem. As a Tool Maker I like to solve problems by making things myself. Just started this thread to see if I was not alone. Turns out that my rifle has a 3 degree forward angle at the tapped holes and the back portion where the screw holes are has a 5 degree rear slope. Re-checking since my last post I determined that the front diameter is 1.163" and the back is 1.625" diameter. Making good progress though. Got the three screw holes drilled and C'bored (2 in front and 1 at rear) and perpendicular slots milled to recess the rings.