Get 10 headshots with the rifle. You can pick up the rifle from bandits on top of the wall or you can find it as a special gun: After the Gatlin gun has blown up head to the rooms to the right around the perimeter of the area. In the furthest back room there will be two rooms that join together with an enemy inside. Shoot the enemy and where the two rooms join together there will be a load of boxes. Remove the boxes and pick up the special weapon. - Superb Scoped Rifle.