The Mark 16 (Mk16) fires a 5.56 mm round, the same size used for decades in M-16s and M-4s. The Mk17 fires a larger 7.62 mm round that is used in some U.S. military machine guns, but it's not the ...

Developed exclusively for U.S. special operations forces and the demanding environments they operate in, the Mk16 Special Operations Forces Combat Assault Rifle is a gas-piston operated 5.56 ...