Under everybody’s radar at this year’s Shooting, Hunting Outdoor trade show in Las Vegas, Colt quietly announced a revamp of its battle-tested M4 military rifle, introducing the new “CM5” rifle to the shooting public.
Firing from an open bolt, and featuring a heavier-than-normal bolt carrier group as well as a shortened barrel, the result of Colt’s modification regime was dubbed the XM231, later officially designated the “SUBMACHINE GUN, 5.56-MM: PORT, FIRING, M231” when adopted by the Army.
Instead of the M16-style layout the Army has been accustomed to since the 1960s, GDOTS took their prototypes in a different direction with the bullpup configuration — the action and magazine located behind the fire control unit of the rifle.