02 Mar 2011 02 Mar 2011
This achievement is easy to do in End of the Road at the part where you go into the base. It has a T-Rex at the front gate (On Multiplayer the level is called Firestorm). Just run past the T-Rex and go through the gate and go to the right where there is ammo and a sniper. Grab the the sniper (if you don't have one already) and go beside the crate nearby. Crouch and scope out ten heads and shoot. You can miss but make sure you get a headshot. If you mess up, reload the checkpoint. If you run out of enemies, go back out through the gate and there should be some leftovers if you didn't kill them already.
In some cases you won't get it because you think you shot them in the head, but it counts as a body shot so just reload and try again. It doesn't take long at all.