SRC SR4 ST Mamba P2 M4 AEG

The M4 carbine is extensively used by the United States Armed Forces and is largely replacing the M16 rifle in United States Army and the United States Marine Corps combat units as the primary infantry weapon. However, the USMC chose the full-sized M16A4 over the M4 as its standard infantry rifle. While ordinary riflemen in the USMC are armed with M16A4, M4 are used by troops in positions where a full-length rifle would be too bulky, including vehicle operators and fireteam and squad leaders.

In 1984, Colt began work on a new carbine design called the XM4 combining the best features of the Colt Commando and M16A2 rifles. In May 1991, the XM4 was renamed the M4. In 1994, the U.S. military officially accepted the M4 into service to replace M16A2 in certain roles. The M4 carbine has also replaced most submachine guns and selected handguns in U.S. military service.