Return to Zero
The ability of a turret or mount to come back to the exact original zero after dialing a correction or removing and reattaching the optic.
Return to zero is the property that lets you dial elevation for a distant target, take the shot, and then crank the turret back to find your point of impact sitting exactly where it started. A scope that fails here leaves you slightly off after every correction, so the error compounds across a string of targets at different ranges. The same idea applies to a qd mount that must reattach to the rifle and place the impact back on the original zero.
Two features help guarantee this behavior. A zero-stop gives the elevation turret a hard mechanical floor, so the shooter can spin down quickly and feel the dial halt precisely at the established setting. Strong, repeatable mechanics and good turret-tracking do the rest, which is why a box test is the standard way to confirm that a scope returns to zero reliably.