The M4 Carbine Assault Rifle: History and Future

A Widely Used Weapon

Soldier aiming rifle
••• John Moore / Getty Images

With the U.S. Defense Department replacing the M4 carbine assault rifle, it is worth looking at the history of this widely used firearm and what weapon might be chosen to replace it.

History and Popularity of the Weapon

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” – is the combat weapon of choice for the U.S. Marine Corps.

The M4 and M16 rifles have 80% of the same parts, making them 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 benefitted from its customization. Current 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.

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.

On July 1, 2009, the U.S. Army took ownership of the M4 design from its manufacturer Colt Defense LLC. Last October, Army officials put forward a number of changes for the M4 design to the U.S. Congress.

Requested changes include a gauge that records the number of shots fired and a heavier barrel.

Contenders to Replace the M4 Assault Rifle

The U.S. Army proceeded in 2010 with an industry-wide competition to replace the M4 assault rifle. As of writing, several leading arms makers are expected to enter the competition with weapons of their own design. Some of the anticipated competitors include:

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 already used by several NATO militaries – notably the French special forces and German commandos.

Barrett REC7: More of an upgrade to the M4 than a new stand-alone rifle, 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. This would cut down on the cost to completely replace the M4, and reduce the amount of money that would need to be spent by the U.S. Army ​on training soldiers to use a brand new rifle.