As in all Halo games you can pull off headshots in Halo: Reach. One lesser known “secret” is that you don’t always have to use a zoom weapon to kill your opponent by shooting their head/face. “Headshooting” – aiming at the face and/or head area while spraying your enemy with ammo – will get the job done more quickly than aiming at the body, though you will use more ammo this way as compared to zoomed shots with, say, a Needle Rifle. While “shooting from the hip” aim for the head or face. Shooting from the hip = shooting with any projectile weapon without zoom by looking through the sights.
For example, if you are facing an Elite with a MA37 Assault Rifle shoot at his face instead of his body. You will eventually kill him with body shots, but aiming for the face gives you the chance for a “lucky headshots” in the middle of spraying that ammo across his face that do more damage and kill him more quickly. Yes, you may miss more often at first as many of your rounds zing over his shoulders, but with practice you will get better at it.
>> Thanks to reader diz whose comment helped improve this post.