7.3 SIGHT ALIGNMENT

With telescopic sights, sight alignment is the relationship between the crosshairs, (reticle), and a full field of view. The shooter must place his head so that a full field of view fills the tube, with no dark shadows or crescents to cause no inaccurate shots. He should center the reticle in a full field of view, ensuring that the vertical cross hair is straight up and down so the rifle is not canted. 
With iron sights sight alignment is the relationship between the front and rear sights. Center the top edge of the front sight blade horizontally and vertically within the rear sight aperture.

























(Thanks to Bill Pierpoint on the CB-BOOK forum for pointing out this section in FM 23-10 “SNIPER TRAINING”.)