Optics and ballistics have been trying to keep up with each other ever since the first shooter realized his iron sights did not match the accuracy of his weapon. The first simple crosshairs have morphed into a variety of different displays that assist the long-distance shooter to estimate size of the target, distance and holdover. Many of the proprietary displays work well (if you understand and practice with the design) but when the US Army decided to incorporate a range-estimation tool into it sniper and riflemen optics, it chose the Mil-Dot system that was being used to range artillery.
Leupold made the M3 Ultra for the US Army with the new Mil-Dot system. Marching to a different drummer, the USMC (US Marine Corps) adopted a similar Mil-Dot design of oblong, not round dots. There are specific differences that can be covered at another time, but let’s just try to get the basics of the Mil-Dots – its theory and practice.
What is a “Mil” Dot? A “Mil” is a milliradian of angle quantified for distance measurement as a “Mil-Dot.” Mil-Dots are used for basically two reasons, to estimate range and holdover for wind (or lateral movement). On military scopes such as the classic Leupold Ultra M3A to the new Konus M30, it is a string of eight dots on the horizontal and vertical crosshairs. Each dot is ¼-mil wide and it is 1-mil from the center of one dot to another or the center of the crosshairs, or the end of the post to the center of the adjacent dot.