M4 Carbine

Lore & Background

The M4 was developed from the XM4, which was based on the XM177E2. The U.S. Army redesignated the XM177E2 to the XM4 Carbine in 1982. The XM4 was tested in June 1983, and prototypes were produced in 1985. The Marines adopted 892 in 1987 with the designation 'carbine, 5.56mm, M4'. The Army gave Colt its first production contracts for M4 carbines in May and July 1993, and for M4A1 carbines in February 1994. The M4 first saw action in Kosovo in 1999 and was used heavily in the war on terror. In the Army, the M4 had largely replaced M16A2s as the primary weapon of forward-deployed personnel by 2005. The U.S. Army decided to largely replace the M16 rifle starting 2010, and the U.S. Marine Corps starting 2016. In April 2022, the U.S. Army selected the M7 rifle to replace the M16/M4.

In Their Own Story

The rain had turned the jungle floor into a brown slurry. Marcus crouched behind a shattered concrete pillar, his M4's suppressor still warm from the three-round burst that had silenced the checkpoint guard. The optic's red dot swam slightly in the humid air. Somewhere ahead, two more hostiles were arguing in low Spanish, boots crunching on wet gravel. He checked the magazine—twelve rounds left. Enough. He eased the foregrip tighter, exhaled, and rolled out of cover, the short barrel tracking the gap between the two figures with the calm certainty of a tool doing exactly what it was built to do.

Reader's Guide

The M4 is a carbine variant of the M16A2, firing 5.56mm ammunition. It has undergone over 90 modifications since 1994, including the M4A1 variant with a thicker barrel and full-auto capability, the SOPMOD accessory kit, and underbarrel weapons such as M203 and M320 grenade launchers and Masterkey and M26-MASS shotguns. The M4 replaced most submachine guns and selected handguns in U.S. military service.

Did You Know?

• The M4 was originally designated the XM4, named as the successor to the M3 carbine.
• Interest in the M4 accelerated after the Battle of Mogadishu (1993), where Rangers found M16s unwieldy but Delta Force members with CAR-15s had no complaints.
• In 2007, the USMC ordered officers up to lieutenant colonel and staff NCOs to carry the M4 instead of the M9 handgun.
• By July 2015, major Marine Corps commands were endorsing switching to the M4 over the M16A4 as the standard infantry rifle.