Scopes with adjustable elevation turrets have become very popular for long-range shooting. One hundred yards is often too close a distance to zero such turrets, since minor deviations cannot be detected. One effective technique is to dial the elevation adjustment to a longer distance—i.e. 300 yds.—and fire a group on target. Adjust any elevation errors using the turret, then loosen the turret so it can be reset to the proper elevation setting for that distance. Tighten the turret and you will have a confirmed zero at distances more appropriate for extended-range shooting.