History of the M4 Carbine Assault Rifle

This Weapon Has Long Been Popular Among Soldiers

Soldier aiming rifle
••• John Moore / Getty Images

Adopted by the U.S. Army in the mid-1990s, the M4 assault rifle is a modern version of the M16, which U.S. soldiers have been using in battle since the Vietnam War. The most current version of the M16 – the M16A2 “Commando” – was at one time the combat weapon of choice for the U.S. Marine Corps.

The M4 and M16 rifles are very similar weapons.  The M4 has proven popular among soldiers because of its compact size, which is helpful in close-quarter firefights and allows for easy movement in combat zones. The M4 uses 5.56-millimeter caliber bullets.

The M4 has also benefited from its customization. Some versions of the rifle offer several attachments, including sight mounts, flashlights, grenade launchers, and shotguns. The rifle has also earned a reputation for having excellent accuracy, out-scoring the rival AK-47 assault rifle in several tests.

M4 Problems in Desert Environments

Despite its popularity, use of the M4 carbine assault rifle in desert environments and urban areas has been problematic. Soldiers in Iraq and Afghanistan have found that the weapon frequently jams in dusty and sandy locations, requiring that the rifle is frequently cleaned and maintained at all times. The age of the weapon coupled with a growing number of complaints has led the U.S. Army to start replacing the M4 assault rifle.

In 2009, the U.S. Army took ownership of the M4 design from its manufacturer Colt Defense LLC. A year later, Army officials put forward a number of changes for the M4 design to Congress. 

Weapons Similar to the M4 Assault Rifle

  • Heckler & Koch HK 416: An assault rifle that was developed by the U.S. Army Delta Force to build on the M4 carbine design with enhancements that reduce misfires and malfunctions. This weapon is used by several NATO members – notably the French special forces and German commandos.
  • Barrett REC7: The REC7 consists of an upper receiver that is attached to the lower receiver of the M4 weapon. Designed by Barrett Firearms Company, the REC7 is compatible with many of the M4’s accessories and offers enhanced night vision and other optics used in combat.  
  • Robinson Armament XCR: Originally developed for U.S. Special Operations Command (SOCOM), the XCR is a multi-caliber weapon that is compact and boasts a gas piston weapon system similar to the AK-47 assault rifle. Changes in caliber can be accomplished by soldiers in only a few minutes during high-stress combat scenarios.
  • Colt ACC-M: Essentially an upgraded M4 assault rifle from the weapon’s manufacturer. The ACC-M has been designed to allow for easy and inexpensive upgrading of the M4 with only the rifle’s upper receiver being replaced.