I just set up ready to shoot, assumeing ammo is known etc & this is for a scope swop zero not a new rifle set up.
Settle down & shoot 3 rounds while aiming at the bull.
Adjust & try again.
Not much help ?
Well perhaps the method info is lacking but I'll tell you to take your time, blating ammo down range to zero is considered a waste of ammo so the quicker you can do it with as few shots as possible the better.
or you can do a no rush job & use every shot as a practice to kill shot as well, every shot aim for the bull, the POI group should still be tight.
A quick 3 or 5 s