All my turrets on my 4.5-14x40 buckmaster scopes are "zeroable", (is that a word?)
-you just unscrew the slotted screw that holds the turret on(enough to pull the turret up past the splines), pull the turret up & off the splines(screw doesn't have to be all the way out!), then line up the turret arrow @ the zero mark, push the turret back down and tighten the screw (doesn't have to be really tight, it can't go anywhere under the caps).