With rifle parallel to floor, and scope base on the action, place bottom of scope on base, if the objective hits barrel, which it usually does, keep placing shims under scope (under turretts) until the objective clears barrel to your liking. With scope clearing barrel and bolt handle on some models, take caliper and measure from top of base to bottom of scope tube. Lets say that number is .250. Now if your using a 30mm tube, divide that number in half. Half of 30mm in decimal is 0.590. 30 x .03937=1.1811. Then divide that number in half which is .590. Then take .590+.250=.840. When buying scope rings, make sure the manufacture measures to center of ring. For example, Seekins makes a low ring which is .820 which is .020 to short. Their medium rings are .870. They will fit with .030 extra height. Different manufactures have different heights. I have used this method for decades on lots of guns and it works. Seems complicated but keeps you from sending rings back in exchange for different height. Hope this helps.
Sling
Sling
