5.56mm M-4 Carbine

The M-4 Carbine is a shortened M-16A2 rifle introduced in 1988. It has replaced about 10 percent of the M-16s in the Army (as of 2003) and has been issued to Marine units selectively. However, it is not intended to completely replace the M-16. The advantage is that the M-4 Carbine is smaller and more compact and most soldiers carrying an M-16 would rather be carrying an M-4. It’s smaller, lighter and is better for shooting out of vehicles.

Carbine, 5.56mm, M-4 fully equipped with M203A1 Grenade Launcher, M68 Reflexive Scope, AN/PVS-14 NVD, PAQ-4 IR Laser
Carbine, 5.56mm, M-4 fully equipped with M203A1 Grenade Launcher, M68 Reflexive Scope, AN/PVS-14 NVD, PAQ-4 IR Laser.

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Description of the M-4 Carbine

M-4 Carbine with IDF rubber bullet attachment
M-4 Carbine with IDF rubber bullet attachment.

The M-4 or M-4A1 5.56mm Carbine is a shortened version of the M-16A2 rifle. It is a lightweight, gas operated, air cooled, magazine fed, selective rate, shoulder fired weapon with a collapsible stock. The M-4 Carbine achieves over 80% parts commonality with the M-16A2 to simplify logistics. It will replace all M-3 .45 caliber submachine guns and for certain service applications, it will replace M-9 pistols and regular M-16 rifles.

The M-4A1 has a rail-mounted forward handgrip, a telescopic stock, a removable carrying handle and Military Standard 1913 (MilStd 1913) accessory mounting rail for night vision sights, combat optics, red-dot laser sights, flashlights or other add-ons, even the M203A1 grenade launcher. The trigger unit is also modified to fire full-auto rather than three-round bursts.

The M-4A1 Carbine Special-Operations Peculiar-Modified (SOPMOD) is described on the linked page.

Characteristics of the M-4 Carbine

USMC M4A1 carbine with 10 inch barrel
USMC M4A1 carbine with 10 inch barrel.

The M-4 Carbine is an anti-personnel weapon designed to be more agile and lighter weight while retaining its lethal effect. Specifications are:

Length, stock retracted 2 ft. 5.79 in.
Length, stock extended 2 ft. 9.49 in.
Weight, w/ sling and one magazine 7.5 lbs.
Bore diameter 5.56 mm.
Maximum effective range, area target 1,968 ft.
Maximum effective range, point target 1,640 ft.
Cyclic rate of fire 825 rounds per minute

Carbine, 5.56mm, M-4A1 showing rail mounting system with accessory equipment
Carbine, 5.56mm, M-4A1 showing rail mounting system with accessory equipment.

Bayonets for the M-4 Carbine

The M-4 Carbine uses the M-7 bayonet which was replaced by the newer M-9 Multipurpose Bayonet System starting in 1987. Since 2002, Marines use the USMC Multipurpose Bayonet (MB). The M-4 Carbine is interchangable with the M-16 for these bayonets.

Russian paratrooper fires M-4 Carbine during joint training exercise with A Company, 2nd Battalion, 502nd Infantry in Lazarevica, Republika Srpska, on 8 December 1999
Russian paratrooper fires M-4 Carbine during joint training exercise with A Company, 2nd Battalion, 502nd Infantry in Lazarevica, Republika Srpska, on 8 December 1999.

M-4 Carbine Grenade Launchers

Both the M203A1 40mm Grenade Launcher and the M320A1 40mm Grenade Launcher are designed to be fitted under the barrel of the M-4 Carbine for additional firepower. See the linked Olive-Drab.com pages for more information on the grenade launchers.

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