M4A1 Carbine
M16-derived carbine with telescoping stock and short barrel. Standard for US special forces and infantry.
M4A1 Carbine
Community
Data trust
- Reliability
- Partially verified
- Sources
- Field Medical Service Technician Student Handbook (M16/M4 family, June 2013)US Marine Corps · Accessed
- Last reviewed
Identity
- Designation
- M4A1 Carbine
- Manufacturer
- Colt / FN Herstal
- Country
- United States
- Year
- 1994
- Category
- Assault rifle
- Status
- In service
Ballistics
- Caliber
- 5.56×45 mm NATO
- Muzzle velocity
- 880 m/s
- Rate of fire
- ~850 rpm
- Effective range
- 500 m
- Maximum range
- 3600 m
Dimensions
- Barrel length
- 368 mm
- Overall length
- 757 / 840 mm
- Empty weight
- 2.9 kg
Mechanics
- Operating system
- Direct gas impingement
- Bolt / action
- Rotating bolt
Feed
- System
- STANAG magazine
- Standard capacity
- 30 rounds
Fire modes
Production & service
- ●M4 — Original version with 3-round burst.
- ●M4A1 — Full-auto, SOCOM heavy barrel, improved trigger.
- ●Mk 18 CQBR — SOCOM short version with 10.3" barrel.
Historical profile
Development
The M4 was developed in the early 1980s as a compact carbine within the M16 family, derived from the Colt Model 720 and the earlier Vietnam-era CAR-15/XM177. It was adopted by the US Army in 1994 as the M4 Carbine.
The M4A1 variant, introduced in the late 1990s and generalized through the 2000s, replaced the three-round burst with full-auto fire and adopted a heavier barrel to handle the sustained fire required by special operations forces.
Design
It retains the M16 direct gas impingement system but with a 368 mm shortened barrel and a 4- or 6-position telescoping stock. The flat-top upper receiver with Picatinny rail has been standard since the SOCOM M4A1 batch.
The SOPMOD program (Special Operations Peculiar Modification) introduced a modular kit of accessories — optics, illuminators, suppressors, M203 grenade launchers — making the M4 one of the most configurable weapon platforms in the world.
Operational service
The M4A1 has been the standard USSOCOM weapon since the 2000s and became the main US Army carbine after the Improved Carbine program. It has been used in Iraq, Afghanistan, operations in Africa and the Middle East, and supplied to dozens of allied forces.
Since 2024 it is being progressively replaced by the SIG Sauer XM7 in 6.8×51 mm in front-line units, but the M4A1 will remain widely in service in support forces and allied nations for the next decade.
Key components
- ●Stock — Telescoping stock on the compact M16-derived M4A1 carbine.
- ●Receiver — Receiver of the M4A1, the fully automatic carbine variant rather than the burst-fire plain M4.
- ●Grip — Separate pistol grip beneath the M4A1 carbine’s lower receiver.
- ●Magazine — Detachable STANAG-pattern box magazine feeding 5.56×45 mm NATO ammunition.
- ●Barrel — Shorter 5.56×45 mm NATO carbine barrel than the M16 rifle.
Community
Recent reviews
Similar systems
M16A4
1997
Daniel Defense M4A1 RIII
2020
K2
1984
SA80 L85A2
1985
Howa Type 89
1989