The Rough Guide to Zeroing

[Timnorris]

This article has very good information about zeroing.....also I want to add an important point that during zeroing if a shooter is not following the correct shooting procedure like trigger pull and front and back sight alingnment for every shot then he will continue dialing his sights and never be able to zero the weapon...this is a point many of us ignore

Zeroing a weapon can be very tricky, that too if the wind is blowing in between, there other factors also like the weapon the ammo and the shooter himself. I would say a cold bore shot which is the first shot should not be counted this would reduce the amount of time taken for zeroing