I sighted it for him and told him to be sure and go to the range to do the final sighting in before deer season. I later learned it was dead on at 100 yards, but he wouldn' t have known that if he hadn' t gone to the range. I think he learned his lesson
Isn' t it amazing how many people still haven' t learned this simple lesson? I sighted my elk rifles in once in TX, then went to Montana to hunt. Naturally, when I got there, the first thing I did was go to a range to check ' em, since travelling can mess up your zero! Both were shooting 3" higher than what I' d set ' em for before leaving home. Since I generally zero my guns +3" @ 100 yards, they would have shot over most game at any range under 300 yards if I hadn' t checked them!!
I start at the scopes lowest power and center the crosshairs. Then I crank up the power and check their position making any small adjustments necessary, then I crank it down again and recheck.
Good method! Also, if you observe the collimator through the scope as you change power settings, you can see if the power change is going to change where your bullet is going to hit!