The Return 2 Zero is built into the elevation cap itself, nothing to mess around with internally therefore no worry about getting dirt/debris inside. As MTEM stated, just loosen the two set screws, rotate the turret back to zero, push back into position and tighten the set screws. After that you'll have 0.5 mils below "0" for easier adjustment if the zero needs slightly adjusted later on for ammo change, altitude, whatever.