I think it depends on what slug gun you have, how far your going to shoot it and how accurate the gun may be... Personally, I use the Zeiss Conquest 3-9x40 on both my slug guns and love them.. Also have a Leupold 2-7 scope made for a slug gun. Most "shotgun scopes" are just parallex corrected for 50 or 75 yards so if your going to zero an accurate slug gun at 100 yards then something like the Zeiss is perfect.. Good Luck...