Science Fair Project Encyclopedia
|Caliber:||5.56 mm NATO|
|Firearm action:||Gas-actuated Rotating bolt|
|Designed by:||Derived from Eugene Stoner's AR-15 design|
|Barrel Length:||14.5 in (368.3 mm)|
|Overall Length:||33.5 in (850.9 mm)|
|Effective Range:||360 m|
|Maximum Range:||3,600 m|
|Cyclic ROF:||700-950 round/min|
|Muzzle velocity:||2,970 ft/s (905 m/s)|
|Mass w/o Magazine:||6.5 lb (2.94 kg)|
|Mass w/ Magazine:||7.5 lb (3.4 kg)|
The M4 Carbine is a shorter and lighter version of the M16A2 assault rifle, achieving 80% parts commonality with the M16A2. As with many carbines, it was meant to provide troops with an effective, shoulder-fired weapon in lieu of pistols, such as the M9. Since the weapon is shorter (and therefore lighter), it is handy and more convenient to carry than a full-length rifle. While this makes it a candidate for non-infantry troops (vehicle crews, clerks and staff officers) it has been used by US Special Operations Command (SOCOM) and others seeking a compact weapon for close quarters combat.
The M4A1 was developed and is produced for the United States government by Colt Firearms, who has an exclusive contract to produce the M4 family of weapons through 2009.
History & Variants
The M4A1 carbine, an improvement upon the M4 carbine intended for Special Operations use, features a fully-automatic fire mode, a flattop NATO M1913-specification rail on top of the receiver (for attachment of optics and other devices), and a detachable rail-mounted carrying handle. The M4A1 can be found in use in many US military units, including the U.S. Army Rangers, the elite Delta Force, U.S. Navy SEALs, and the United States Marine Corps Force Reconnaissance companies. Variants of the carbine built by different manufacturers are also in service with the Australian Special Forces, South Korea, and the infantry forces of several other countries.
The M4A1 Carbine is specially favored by counter-terrorist and special forces units because of its compactness and firepower that the rifle offers for close quarters combat (CQB). It is very useful in urban warfare. Although the M4 does not have as far an effective range as the longer M16, many military analysts consider engagement with a non-specialized small arm above a range of 300m to be unnecessary.
The Special Operations Peculiar Modification (SOPMOD) I M4A1 Kit was developed by USSOCOM for use with units under its jurisdiction. The kit features an M4A1 rifle, a Rail Interface System (RIS) handguard system developed by Knight's Armament Company (KAC), a shortened quick-detachable M203 grenade launcher and leaf sight , a KAC silencer, KAC rear back-up sight, an Insight Technologies AN/PEQ-2A visible laser/infrared designator, along with Trijicon ACOG, Reflex optics and a nightvision sight. This kit was designed to be configurable (modular) for various missions and the kit is in service right now with Special Operations units (though many soldiers have changed the Trijicon Reflex sight for M68 Aimpoint red dot sights and EOTech holographic sights).
A 2nd generation SOPMOD (now known as SOPMOD II ) is currently under development, with many different manufacturers competing for a contract. Notable manufacturers include Knight's Armament Company and their URX II, ARMS and their Selective Integrated Rail (SIR) system, along with Lewis Machine & Tool's Monolithic Rail Platform (MRP).
The M4/M4A1 5.56 mm Carbine is a gas operated, air cooled, magazine fed, selective rate, shoulder fired weapon with a collapsible stock. A shortened variant of the M16A2 rifle with a 36 cm barrel, the M4A1 provides the individual soldier operating in close quarters the capability to engage targets at extended range with accurate, lethal fire. The original M4 Carbine had "semi" and three round burst fire modes, while the M4A1 has "semi" and "auto" but no three-round burst. The M4A1 Carbine achieves over 80% commonality with the M16A2 Rifle and was intended to replace M3 .45 ACP submachine guns and selected M9 pistols and M16 rifle series (though this plan may be changed with the development of the XM-29 OICW and the XM8 carbine with most Army units.) It is capable of mounting the M203 Grenade Launcher.
Some features compared to a full length M16A2 rifle include:
- Compact size
- Shorter barrel
- Collapsible butt-stock
- Higher rate of fire
- Selective full-automatic rather than three shot bursts (M4A1)
However, there have been some criticisms of the carbine, such as lower bullet velocities and louder report due to the shorter barrel, additional stress on parts because of the shorter gas system, and a tendency to overheat faster than the M16A2.
Like all the variants of the M16 assault rifle, the M4 Carbine and the M4A1 Carbine can be fitted with many accessories such as night vision devices, laser pointers, scopes, bipods, the M203 grenade launcher and the XM-26 LSS shotgun.
The operating drills for the M4 are identical to those of the M16
Safety Precaution (no magazine fitted)
Safety precautions should be performed when taking possession of the weapon from another user, or any time the state of the weapon is unknown or in doubt. Always assume for safety purposes that such a weapon has a round in the chamber, ready to fire. Point the weapon in a safe direction, pull the cocking handle to the rear (a round may be ejected) and hold it there, examine the chamber to ensure it is clear, allow the action to go forward under control, push the forward assist, fire the action, and close the ejection port cover.
Safety Precaution (magazine fitted)
Perform an "unload". If the above safety precaution is used with a charged magazine fitted a round will be chambered and fired.
Insert a charged magazine into the magazine housing. There is a slight audible click when the magazine is properly fitted. The secureness of the magazine can be tested by gently trying to remove the magazine.
Pull the cocking handle all the way to the rear and release. Push the forward assist. If the weapon is not to be fired immediately then put the fire selector to "SAFE" and close the ejection port cover.
Marksmanship is a complex and subtle art and is beyond the scope of this article. However, in general the weapon is fired by putting the fire selector on either "SEMI" or "BURST" ("AUTO" on the M4A1), resting the butt plate against the shoulder, aligning the eye of the firer, aperture of the rear sight, tip of the foresight, and target, and squeezing the trigger.
Attempt to put the fire selector on "SAFE" (the selector will only go on "SAFE" if the hammer is depressed, ie: the weapon is cocked). Remove the magazine by pressing the magazine release with the trigger hand while grasping the magazine with the other hand. Tilt the weapon to the right and cock the weapon (a round may be ejected). Pull the cocking handle to the rear again and hold it. Tilt the weapon to the left and ensure the chamber is empty. Allow the action to go forward, push the forward assist, put the fire selector to "SEMI" and squeeze the trigger. Close the ejection port cover and recover the ejected round.
- M16, AR-15, CAR-15, XM-177, Colt Commando.
- M1 Carbine, carbine, assault rifle
- List of individual weapons of the US Armed Forces
- List of crew served weapons of the US Armed Forces
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