I did a little bit of surveying in school. We used a transit and stadia rod to determine distances. A calibrated mil-dot scope acts as a very good substitute for a transit scope. The only problem is the stadia rod (our target). I have a variety of features that I have learned the dimensions of. If there is a known target like a Gamo squirrel in open view, it can be ranged more accurately with mil-dot spacing then by the optical clarity of a high powered scope. It takes a little bit of math, but it is very precise. Half the time there is some feature present that allows me to range precisely with mil-dots. If not, I just take my best guess.