You can also go here and let the computer do it for you--
http://www.twincityrodandgun.com/Sc...Scope%20Mounting%20Tilt%20Calculator.htm

The calcs for me have been fairly close for offset. You can also fine tune the Burris offset insert system to your hearts content by adding plastic credit card, coke can [both plastic and alum.) shim between scope tube and insert.

I bought a bunch of Signature rings a few years ago and got the gunsmith's offset insert kit that provides for a lot of inserts.