Mils Per Revolution
How much elevation a single full turn of a scope turret provides, which sets how many turns you need to reach a given distance.
Mils per revolution is the total elevation, measured in milliradians, that one complete turn of an elevation turret delivers before the dial returns to its starting mark. A turret graduated in tenth-mil clicks with ten mils per turn covers a lot of trajectory per turret revolution, while a finer-pitched turret with five mils per turn needs two turns for the same correction. Knowing the value tells you exactly where the trajectory will land you on the dial at any range.
This figure matters most for dialing to distant targets, because a tall correction can run you past the end of the first revolution and onto the second, where it is easy to lose track of which turn you are on. Scopes with more milliradian travel per turn keep more of the usable range on a single rotation, simplifying the count. It is a core spec to check when matching an optic to the trajectory you intend to shoot.