M4 carbine Wikipedia
The M4 Carbine is a #215;45mm NATO, aircooled, gasoperated, direct impingement, magazinefed has a in (370 mm) barrel and a telping is essentially a lighter and shorter variant of the M16A2 assault rifle.. The M4 is extensively used by the United States Armed Forces and is largely replacing the M16 rifle in United States Army and United States Marine Corps