Charlie Watson said:I've used this method for years. It works well.
With your scope rail mounted on the rifle, stack two equal amounts of washers (or pennies) at the location of where you will mount the rings. Place your scope on the stacks and add additional pennies until you have the desired height. Measure the stacks with a caliper and you will have your saddle height above the base. If your rings are sold with a measurement from base to center of ring, just add .59055 to your original measurement for a 30mm tube. Done. Buy your rings with the closest measurement to your set up.
After using several types of rings, the Nightforce Ultra Light Rings are the best for me. Don't forget to lap any rings you get.