Zero the scope at 100 yards. Remove the turret, slide the shims in, and keep adding as tight as you can get them alternating the openings. Once you have the gap filled up with shims reinstall the turret with zero on the turret matching zero on the scope body. Now you can dial impact "up" all you want, but you cannot dial below your zero, the turret will stop just below your zero, probably less than 1.0 Mil. That is a zero stop turret.
800 Yard Steel Range
Precision Rifle InstructionMemberships and Classes Available