Reticle Ranging
Estimating distance to a target by measuring its apparent size against the calibrated marks of a reticle, then solving with a ranging formula.
Reticle ranging is the practice of judging distance by measuring how much of the reticle a known-size target covers. The shooter notes the subtension the target spans, in mils or in minutes, and feeds that measurement into the mil relation formula along with an estimate of the target’s true size. The output is a usable range without any electronics.
This skill predates and backs up the laser range finder, and it remains valuable when batteries fail or when a target will not return a clean laser reading. Its weakness is that it relies on a good size estimate, so a marksman practices on objects of standard dimensions to keep the method honest and repeatable.