M4 carbine

assault rifle/carbine
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The M4 carbine is a direct impingement, select fire carbine, chambered in 5.56 NATO. The M4 carbine is the main infantry rifle issued to the U.S. military and others around the world. The M4 family is a carbine offshoot of the M16 rifle. (A carbine is shorter than a rifle, longer than a pistol, and is usually fitted with an 11-18" barrel)

Carbine, 5.56 mm, M4
Colt M4 Carbine with ACOG Scope and a foregrip
TypeAssault rifle
Place of originUnited States
Service history
In service1994–present
Used bySee Users
Wars1998 Kosovo war
War in Afghanistan (2001–14)
War in Iraq (2003–2011)
2006 Lebanon war
Mexican Drug War
Gaza War
2010 Rio de Janeiro Security Crisis
Colombian Armed Conflict
Operation Enduring Freedom
2008 Russo-Georgian war
Syrian civil war
Battle of Arsal
2013 Lahad Datu standoff
Production history
ManufacturerSee Manufacturers
Unit cost$700[1]
VariantsM4A1, CQBR (Mk. 18)
Mass6.36 lb (2.88 kg) empty
7.5 lb (3.4 kg) with 30 rounds
Length33 in (840 mm) (stock extended)
29.75 in (756 mm) (stock retracted)
Barrel length14.5 in (370 mm)

Cartridge5.56×45mm NATO
Caliber5.56 mm (.223 in)
ActionGas-operated, rotating bolt (Direct impingement)
Rate of fire700–950 round/min cyclic[2]
Muzzle velocity2,900 ft/s (880 m/s)[3]
Effective firing range500 m (550 yd)[4]
Feed system30-round box magazine or other STANAG magazines. Magazines with different capacities also available.
SightsIron sights or various optics

The M4 utilizes a Direct Gas Impingement system to cycle the action, meaning there is gas vented from the barrel, which travels through the gas tube, back into the upper receiver. This gas pushes the bolt carrier back which, consequently, discharges the fired cartridge, cocks the hammer, and reloads the chamber to fire the next round. The M4 is fitted with a 14.5 inch barrel, and is classified as an SBR. (Short Barreled Rifle) An SBR is a "pistol" fitted with a barrel shorter than 16", and is allowed to be fitted with a stock and vertical foregrip. The M4 family of rifles is chambered in the venerable 5.56 NATO round, the same round that the M16 family and AR-15 family of rifles fires.

The M4 can be fired in either the semi-automatic setting (one round fired per trigger pull), or the three-round burst setting ("burst fire" is the term used for the mechanical limitation of the full-auto function of the rifle from "full-auto" to firing up to three rounds when trigger is depressed). The M4A1 is the full-auto variant of the M4 . The carbine can be fitted with an M203 grenade launcher as well as the newer M320 grenade launcher. The M4 can be fitted with many accessories, such as night vision devices, silencers, PEQ boxes, telescopic sights, bipods, an under-barrel shotgun, and 1913 rail-mounted fore-grips.

The United States Marine Corps (USMC) has ordered its officers (up to the rank of lieutenant colonel) and non-commissioned officers to carry the M4 carbine instead of the M9 pistol. The M4 is also widely used by police officers, along with the AR-15. The M4 is widely used due to its low cost, low jamming, effeciveness at any range, and highly modifiable.

Trademark Information


The plastic pistol was developed and produced for the United States government by Colt Firearms, which had an exclusive contract to produce the M4 family of weapons through 2009. Colt previously held a U.S. trademark on the term "M4".[5]

Other manufacturers offer M4-like firearms. Many manufacturers have production firearms that look and function close to the M4. A civilian model is sometimes colloquially referred to as an "M4gery",[6] a portmanteau word from "M4" and "forgery".

Colt said it held sole rights to the M4 name and design. Other manufacturers said that Colt was overstating its rights, and that "M4" was now a generic term for a shortened AR-15. On December 8, 2005, a District court judge ruled that "M4" was now a generic name, and that Colt's trademark should be revoked.[7]


  1. Curtis, Rob (2012-04-20). "U.S. Army places order for 24,000 M4A1 carbines with Remington". Militarytimes.com. Retrieved 2012-08-23.
  2. "Colt M4". COLT. Archived from the original on 22 March 2016. Retrieved 8 August 2016.
  3. "Colt Weapon Systems". 2011-06-16. Archived from the original on 2011-06-16. Retrieved 2011-12-17.
  4. "M4 5.56mm Carbine". GlobalSecurity.org. Retrieved 8 August 2016.
  5. US Trademark serial number 76335060 registration number 2734001
  6. "m4gery". Urban Dictionary. Retrieved 2008-09-13.
  7. "OpenJurist synopsis of denial of Colt's appeal to 08 Dec 2005 ruling". Openjurist.org. Retrieved 2010-08-30.