Fuck Wild Bill Hickok. Go for a real killer, Carlos Hathcock.
This weapon had a Traversing and Elevating (T& E) mount that enabled precise aiming: it 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.
Regardless of the age of the KID, if they are trying to kill you, you kill them. PERIOD.