M16A4
FN America · Assault Rifle · In Production · 1997
Also known as: Rifle, 5.56mm, M16A4, AR-15A4
Overview
The M16A4 is a selective-fire, gas-operated assault rifle chambered in 5.56x45mm NATO. Adopted by the U.S. military in 1997, it is the fourth generation of the M16 series and served as the primary service rifle for the U.S. Marine Corps from 1997 to 2015. The M16A4 features a detachable carrying handle with integrated rear iron sights and a full-length MIL-STD-1913 Picatinny rail on the flat-top upper receiver for mounting optics and accessories. It utilizes direct impingement gas operation with a rotating bolt, has a 20-inch chrome-lined barrel with 1:7 rifling twist optimized for NATO SS109/M855 ammunition, and a KAC M5 quad-rail handguard for additional accessory mounting. The rifle has safe, semi-automatic, and 3-round burst fire modes, and is compatible with the M203 40mm grenade launcher. With over 8 million M16 variants produced and used by over 80 countries, the M16A4 represents the culmination of decades of refinement to Eugene Stoner's original AR-15 design.
Specifications
| Weight (empty) | 3400 g (119.9 oz) |
| Weight (loaded) | 3856 g (136.0 oz) |
| Overall Length | 1003 mm (39.49") |
| Barrel Length | 508 mm (20.00") |
| 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 | 1798 J (1326 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 · 5.56x45mm NATO — also known as 5.56mm NATO, 5.56x45mm, .223 Remington, SS109, M855
Features
- Firing modes: Semi Automatic, Burst 3
- Feed systems: Detachable Box Magazine
- Safety mechanisms: Manual Safety Selector, Half Cock Notch
- Features: Select Fire, Three Round Burst, Detachable Carrying Handle, Accessory Rail, Picatinny Rail, Chrome Lined Barrel, Chrome Lined Chamber, Rotating Bolt, Flat Top Receiver, Quad Rail Handguard, M203 Grenade Launcher Compatible
Variants
- M16A3 — Full Auto
- Mk12 SPR Mod 0 — Designated Marksman
- Mk12 SPR Mod 1 — Designated Marksman
- M16A4 MWS — Modular Weapon System
Service history
Operators
- United States Marine Corps · adopted 1997
- United States Army · adopted 1997
- United States Navy · adopted 1997
- United States Air Force · adopted 1997
- Philippine National Police
Conflicts
- War in Afghanistan (2001-2021)
- Iraq War (2003-2011)
Production
Estimated total produced: 8,000,000 · Production years: 1997-present
Total for all M16 variants; M16A4 produced by FN America and Colt
Origin
Country of origin: United States
Designer: Eugene Stoner
Notes
The M16A4 differs from the M16A2 primarily in its modular flat-top receiver design that allows for easy optic mounting via Picatinny rail, replacing the fixed carry handle of earlier variants. The M16A3 variant is identical to the M16A4 but features full-automatic fire instead of 3-round burst. Primary production shifted from Colt to FN America in 1988, with both companies now 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 in 2015, with remaining M16A4s reassigned to support and non-infantry units. The Mk12 SPR variants are specialized designated marksman rifles based on the M16A4 platform with match-grade 18-inch barrels and enhanced accuracy features.
Background
The M16A4 represents the culmination of the AR-15 platform that Eugene Stoner originally designed in 1956. Its flat-top receiver with Picatinny rail was a game-changer for modularity, allowing Marines and soldiers to mount any optic system. The USMC used the M16A4 as their primary rifle until 2015, when they finally transitioned to the shorter M4 carbine.