Deep ends. What power is the rifle putting out, what weight of pellets are being used. On a couple of my 177 combos I zero at 32 yards because that gives the the max length of "on cross hairs" aim points, - I just have to remember a little bit of hold under at 19-22 yards.
With .22 my zero is abt 23 yard.
But there again, I'm a crappy shooter