The M4 Rifle is a 14.5" barreled select-fire assault rifle adopted by the United States Armed Forces that first appears in Book 1: The Gray Man.
Overview[]
The M4 is a 5.56×45mm NATO, air-cooled, Stoner expanding gas system (commonly misidentified as direct impingement), gas-operated, magazine-fed carbine. It has a 14.5 in (370 mm) barrel and a telescoping stock. The M4 is also capable of mounting the M203 and M320 grenade launchers.