Long range is the best time to utilize firearms. Being able to take careful aim will eliminate ammo loss from “spray and pray.” Here are a few tips to make head-shots easier.
1) Keep the rifle against your shoulder, but don’t force it.
2) If possible, rest the forestock on something stationary; if not don’t make your grip too firm.
3) Align your front and rear sights carefully.
4) Inhale, then squeeze the trigger slowly at the end of your exhale. The weapon should surprise you when it fires.
5) Reload, if necessary.
6) Assess the situation and fire again.
Source: Sean Roberts (Bootcamp) Personal Experience: ROTC