[4EVERM-14]

Same thought as STEVE SMITH posted. There are witness marks on the receiver and one on the sight base. I like to center the the witness marks then sight the rifle for windage zero by moving the front sight only. Add a nailpolish line and that gives an easy to find Mechanical Windage zero. Another nailpolish line across the windage knob and receiver for reference. The rifle should then give you about 17 minutes of windage each way. So far I've only had to add 8 minutes for wind, but that was one heck of a day!
Sight the rifle for elevation at whatever distance you like. Say 200yds.
Count the number of clicks back down to the bottom and remember it. With bottom as Mechanical zero that number of clicks up should be put back to center at 200yds. The M1, M14-M1A sights are reliable and repeatable. If you keep a diary or score book keep track of the yardage, sight settings and type of ammo. Those sight settings will repeat quite closely provided the same ammo is used.