Abstract: A scope for a weapon or firearm includes an elevation adjustment turret device having a rotatable elevation adjustment knob connected to a gear mechanism via a distance-indicating dial. Rotation of the knob displays to a user a distance to a target which is usable to distance-calibrate the scope for projectile accuracy at that target. The gear mechanism includes a planetary gear mechanism. The turret device includes an indexing mechanism constructed and arranged so as to be selectively configurable in each of at least two indexing modes. In a first indexing mode, the elevation adjustment knob is substantially prevented from rotating, and in a second indexing mode, the elevation adjustment knob is rotatable in an indexing mode selected from at least one of stepped rotation, and/or free unhindered rotation.