M4 carbine|M4
The M4 Carbine is a 5.56×45mm NATO, air-cooled, gas-operated, direct impingement, magazine-fed, select fire carbine. It has a 14.5 in barrel and a telescoping stock. It is essentially a lighter and shorter variant of the M16A2 assault rifle. Wikipedia
Length: 33 in (838 mm) (stock extended); 29.75 in (756 mm) (stock retracted)
Caliber: 5.56 mm (.223 in)
Produced: 1987–present
Rate of fire: 700–950 round/min cyclic
Muzzle velocity: 2,970 ft/s (910 m/s) (M855A1 round); 2,887 ft/s (880 m/s) (M855 round); 2,986 ft/s (910 m/s) (M193 round)
Action: Gas-operated, rotating bolt, Stoner expanding gas