This Cabela's scope, 4 x 12 x 44, is the first I've ever owned with the third turret (left side). It has various yardages on it, from 25 to infinity. Friend says it's to automatically change the reticle to zero and thus compensate for bullet drop at each of those distances. I said I thought it was for parallax adjustment and if so it should be set for the range I zeroed it for. Any help on this? Seems like a pretty decent scope.
Your friend is confused, it is not a bullet drop, as that would be a specific turret designed for a particular load and location. You are correct, it is a parallax adjustment. This vid explains how to adjust it.
Come to think of it, maybe you could adjust bullet drop for infinity - just coordinate the drop perfectly with the curvature of the earth, then generate enough velocity so the bullet would eventually come back around and hit you square in the a**!