Colt M16A4
Colt's Manufacturing Company · Assault Rifle · In Production · 1994
Also known as: Rifle, 5.56mm, M16A4, Colt Model 945, AR-15A4
Overview
The Colt M16A4 is the fourth and final major variant of the M16 family of assault rifles, adopted by the U.S. military in the late 1990s. Its primary advancement over the M16A2 is the replacement of the fixed carrying handle with a detachable carry handle mounted on a full-length MIL-STD-1913 Picatinny rail on a flat-top upper receiver, enabling quick mounting of optical sights, red dot sights, and night vision devices. The M16A4 retains the M16A2's 20-inch chrome-lined barrel with 1:7 rifling twist, three-round burst capability, and direct impingement gas system. It was commonly equipped with the Knight's Armament Company M5 RAS (Rail Adapter System) quad-rail handguard, providing four additional Picatinny rail surfaces for mounting foregrips, lights, lasers, and other accessories. The M16A4 served as the standard-issue rifle of the United States Marine Corps from 1998 until approximately 2015, seeing extensive combat in Iraq and Afghanistan. Production was shared between Colt and FN America.
Specifications
| Weight (empty) | 3400 g (119.9 oz) |
| Weight (loaded) | 3860 g (136.2 oz) |
| Overall Length | 1003 mm (39.49") |
| Barrel Length | 508 mm (20.00") |
| Height | 248 mm (9.76") |
| Width | 64 mm (2.52") |
| Action Type | Gas Operated Direct Impingement |
| Firing Mechanism | Hammer Fired |
| Trigger Type | Single Stage |
| Magazine Capacity | 30 rounds |
| Magazine Type | Detachable Box |
| Muzzle Velocity | 948 m/s (3110 fps) |
| Muzzle Energy | 1796 J (1325 ft·lbf) |
| Effective Range | 600 m (656 yd) |
| Maximum Range | 3600 m (3937 yd) |
| Rate of Fire | 800 rpm |
| Barrel Rifling | Right Hand |
| Rifling Twist | 178 mm (7.01") |
| Number of Grooves | 6 |
| Frame Material | Aluminum Alloy |
| Barrel Material | Steel |
| Stock Material | Polymer |
| Finish | Hard Anodized |
Calibers
- 5.56x45mm NATO · primary · SS109 / M855 — also known as 5.56 NATO, 5.56x45, .223 Remington
Features
- Firing modes: Semi Automatic, Burst 3
- Feed systems: Detachable Box Magazine
- Safety mechanisms: Manual Safety Selector, Half Cock Notch
- Features: Fixed Stock, Select Fire, Three Round Burst, Chrome Lined Barrel, Chrome Lined Chamber, Rotating Bolt, Direct Impingement Gas System, Flat Top Receiver, Picatinny Rail, Detachable Carrying Handle, Quad Rail Handguard, Forward Assist, Brass Deflector, Birdcage Flash Hider, Pistol Grip, Inline Stock Design, M203 Grenade Launcher Compatible
Variants
- Colt M16A2 — Predecessor
- M16A3 — Full Automatic
- Mk 12 SPR Mod 0 — Designated Marksman
- Mk 12 SPR Mod 1 — Designated Marksman
- M4 Carbine — Carbine
- M4A1 Carbine — Carbine
Base model
Service history
Operators
- United States Marine Corps · adopted 1998 · as M16A4
- United States Army · adopted 1998 · as M16A4
- United States Navy · adopted 1998 · as M16A4
- United States Air Force · adopted 1998 · as M16A4
- Philippine Armed Forces · adopted 2002 · as M16A4
- Lebanese Armed Forces · adopted 2006 · as M16A4
- Afghan National Army · adopted 2003 · as M16A4
- Iraqi Armed Forces · adopted 2004 · as M16A4
- Georgian Armed Forces · adopted 2007 · as M16A4
- Royal Thai Armed Forces · adopted 2005 · as M16A4
- Colombian National Army · adopted 2005 · as M16A4
- Salvadoran Armed Forces · adopted 2006 · as M16A4
Conflicts
- War in Afghanistan (2001-2021)
- Iraq War (2003-2011)
- War on Terror (2001-present)
- Second Battle of Fallujah (2004)
- Battle of Marjah (2010)
- Philippine insurgency (2000-present)
- Russo-Georgian War (2008)
Production
Estimated total produced: 2,000,000 · Production years: 1994-present
Produced by both Colt and FN America for US military and foreign military sales. Part of over 8 million total M16-family rifles. Many surplus M16A4s transferred to allied nations through security assistance programs.
Origin
Country of origin: United States
Designer: Eugene Stoner
Notes
The M16A4 differs from the M16A2 primarily in its modular flat-top receiver design. The detachable carrying handle contains the same rear sight assembly as the M16A2 and can be removed in seconds to mount optics directly to the Picatinny rail, giving the rifle the lowest possible optic mounting height. The flat-top receiver also reduced the rifle's weight slightly compared to the M16A2's heavier forged carry handle. The M16A3 variant is identical to the M16A4 but features full-automatic fire instead of 3-round burst, used primarily by the U.S. Navy SEALs. Primary production shifted from Colt to FN America in 1988 under a competitive contract, with both companies producing the rifle for military and foreign military sales. The U.S. Marine Corps transitioned from the M16A4 to the M4 Carbine as their standard infantry weapon beginning in 2015, and eventually adopted the M27 IAR (HK416 variant) as its standard infantry automatic rifle. Many surplus M16A4s were transferred to allied nations through foreign military assistance programs.
Background
The M16A4 represents the culmination of the M16 platform's evolution before the military transitioned to the shorter M4 carbine. Its flat-top Picatinny rail was a game-changer for modularity, allowing Marines to mount the ACOG (Advanced Combat Optical Gunsight) that became the iconic sight of the Iraq and Afghanistan wars. The 4x Trijicon ACOG TA31 mounted on an M16A4 became the definitive image of the US Marine in combat during the 2000s. The KAC M5 RAS quad-rail handguard transformed the rifle into a modular weapons platform, but its sharp-edged aluminum rails were infamous for tearing up hands and equipment, leading to widespread use of rail covers. Marines deeply debated whether the full-length M16A4 or the shorter M4 was the better combat weapon, with the M16A4's longer barrel providing superior accuracy and muzzle velocity at range. The USMC was the last major US service to retain a full-length rifle as its standard arm before finally transitioning to the M4 and then the M27 IAR.