At the range and having a hell of a time with my 3-20 Ultra Short. I’m trying to set the elevation zero stop but can’t get it to work. I’m zeroed at 12 mils up. I lock the turret, and loosen the two 2mm Allen head screws. I’ve tried barely loosening them, and have had them as far out as I can while still being able to unlock the turret. I then turn the turret back to zero, lock it, and tighten the two screws. Each time the round hits 12 mils low. What am I doing wrong here?