Read about Carlos Hathcock
On some occasions, however, he used a different weapon: the .50-caliber M2 Browning Machine Gun, on which he mounted the Unertl scope, using a bracket of his own design.[verification needed] This weapon was accurate to 2500 yards when fired one round at a time. At one point, he took careful aim at a courier carrying a load of assault rifles and ammunition on a bicycle. He had second thoughts when he saw a 12-year-old boy in his sights, but after considering the intended use of those weapons, he decided to disable the bicycle, hitting the bike frame. The boy tumbled over the handlebars, grabbed a gun, and immediately began firing back, so Hathcock returned fire, killing him. (Source Marine Sniper,