Turret Revolution
Also: Second Rotation
One full turn of an elevation turret; distant targets can demand more than one, where a zero stop helps the shooter track which rotation they are on.
A turret revolution is a single complete rotation of the elevation turret, and it represents a fixed block of adjustment such as a number of mils or minutes per turn. The total a turret offers per revolution, its mils per revolution, determines how far you can dial before the knob comes back around to where it started. Far targets at extreme range often need more elevation than one turn provides, which puts the shooter into a second rotation.
The danger of a second rotation is losing track of which turn you are on, because the markings repeat and a full revolution of error puts the shot wildly high or low. A zero stop gives a firm reference at the zero so you always know your baseline, and many turrets add a visible indicator that shows the current rotation. Clear dialing habits, confirmed against a range card, are what keep multi-revolution corrections honest under pressure.