Assault Rifle, 5.56 mm, XM177
USAF Airman with a GAU-5/A (Colt Model 610)
Type Carbine Place of origin United States Service history In service 1968–present Production history Designed mid-1960s Manufacturer Colt Manufacturing Company Specifications Weight Empty: 5.2 lb. (2.36 kg)
Loaded w/30 round: 6.22 lb. (2.82 kg)
Length Buttstock retracted: 28.3 in. (719 mm)
Buttstock extended: 31 in. (826 mm)
Barrel length 10 in. (254 mm) Cartridge 5.56x45mm NATO Action Direct impingement Rate of fire 700 to 900 rounds per minute Muzzle velocity 2,750 ft/s (838 m/s) Feed system Various STANAG Magazines. Sights Rear: Flip aperture
The Colt Automatic Rifle-15 Military Weapons System or CAR-15 was a family of AR-15 and M16 rifle–based firearms marketed by Colt in the late 1960s and early 1970s. Due to their compact size, the short-barreled Colt Commando and XM177 versions of this family continued to be issued to the U.S. military after the Vietnam War.
The CAR-15 name was an attempt to re-associate the AR-15 name with Colt, since the AR initially stood for ArmaLite Rifle, the original manufacturer. Colt later abandoned the CAR-15 concept, but continued to make variations, using the M16 brand for military-oriented models and the Colt AR-15 brand for law enforcement and civilian models. However, in present usage, CAR-15 is used as a generic name for carbine-length M16 and AR-15 variants.
Specifically, "Colt Commando" currently refers to the ultrashort 11.5-inch barrel assault rifle of the Model 733 series. By comparison, the M4 Carbine has an 14.5-inch barrel, while that of the M16 assault rifle is 20 inches (0.51 m).
- 1 History
- 2 CAR-15 Military Weapons System
- 3 Post-Vietnam
- 4 Gallery
- 5 References
- 6 Further reading
- 7 External links
Starting in 1965, Colt attempted to market the M16 rifle as a modular weapons platform that could fulfill all of the various needs of an army, similar to the marketing plans for the AR-10, its predecessor, and the Stoner 63, its rival. In order to compete with the Stoner 63 which could be converted into a belt-fed light or medium machine gun, Colt also included the short-lived CMG-1 and CMG-2 machine guns in the CAR-15 Military Weapons System, though the CMG-1 and CMG-2 had few parts in common with the CAR-15s. By using various upper assemblies, buttstocks, and pistol grips, the weapon could be configured as an assault rifle, a heavy-barreled automatic rifle, a carbine, a submachine gun, or as a survival rifle.
Each variation had a Colt model number, meant for internal identification usage. The members of the CAR-15 family, with the exception of the Rifle and Commando, only existed as toolroom prototypes and never entered full-scale production. As a result, wide variation due to experimentation exists within each model. The U.S. military only made significant purchases of the Rifle and Commando versions, so Colt abandoned the CAR-15 family concept. The CAR-15 Rifle was already identified by most users as M16s or AR-15s, and the CAR-15 name was similarly associated with the short-barreled Submachine Gun and Commando models. Because of that, the term "CAR-15" has been used to describe any M16-based carbine, even if the particular weapon is not officially named thus.
CAR-15 Military Weapons System
The Model 603 CAR-15 Rifle, adopted initially by the United States Army as the XM16E1 and then later as the M16A1, and the Model 604 CAR-15 Rifle, adopted by the United States Air Force as the M16, formed the core of the CAR-15 family. However, the United States military had already committed to purchases before Colt created the concept of the CAR-15 weapons system. The principal difference between the Model 603 and Model 604 is that the former has a forward assist, allowing a user to manually close the bolt.
CAR-15 Carbine Type Carbine Place of origin United States Specifications Weight Empty: 6.0 lb (2.72 kg) Length 33.6 in (853 mm) Barrel length 15 in (381 mm) Muzzle velocity 3,050 ft/s (930 m/s)
The Model 605A CAR-15 Carbine was a shortened version for situations where longer weapons could be unwieldy, such as aboard vehicles or helicopters. The only significant change from the M16 rifle was that the barrel was shortened to 15 inches in length, so that it ended just forward of the front sight base. Because of the shorter barrel, no bayonet mounting lugs were provided. One prototype used a shorter handguard and a 16-inch long barrel.
The Model 605B had no forward assist, but had a four-position selector switch (developed by Foster Sturtevant in December 1966) so that a user could select safe, semi-automatic, three-round burst, or full automatic modes of fire. Unlike the standard three-position group, the four-position group went from (going clockwise from the 9 o'clock position) safe, fully automatic, semi-automatic and finally burst. The selector itself had 360 degrees of motion, and could be moved either clockwise or counterclockwise, unlike with standard groups. Instead of three-round burst, the burst cam could be modified to two-round or six-round burst. Both versions used the rifle-length buttstock.
CAR-15 Heavy Assault Rifle
The Model 606 CAR-15 Heavy Assault Rifles used heavy barrels (HBAR) for sustained automatic fire. Like the Browning Automatic Rifle (BAR), the CAR-15 HBARs did not have a quick-change barrel. The HBARs could be fitted with either a Colt bipod, a M14 rifle M2 bipod, or a modified BAR bipod.
CAR-15 Heavy Assault Rifle M1
CAR-15 Heavy Assault Rifle M1 Type Automatic Rifle Place of origin United States Specifications Weight Empty: 7.5 lb (3.4 kg) Length 38.6 in (980 mm) Barrel length 20 in (508 mm) Muzzle velocity 3,250 ft/s (991 m/s) Feed system 20-round box magazine
The CAR-15 Heavy Assault Rifle M1 used 20-round M16 box magazines, which limited its ability to provide sustained rates of automatic fire. The 30-round M16 box magazine was not available until 1969. The Model 606A had a forward assist. The Model 606B had a forward assist and the four-position selector. The Army purchased fewer than 200 Heavy Assault Rifle M1s for use in the Small Arms Weapons Systems (SAWS) tests in 1965.
CAR-15 Heavy Assault Rifle M2
CAR-15 Heavy Assault Rifle M2 Type Automatic Rifle Place of origin United States Specifications Weight Empty: 8.3 lb (3.76 kg) Length 38.6 in (980 mm) Barrel length 20 in (508 mm) Muzzle velocity 3,250 ft/s (991 m/s) Feed system 50- or 120-round belt
The CAR-15 Heavy Assault Rifle M2 was a belt-fed version using heavily modified upper and lower receivers. Colt engineer Rob Roy designed a special ammunition box to hold a 50-round or 120-round ammunition belt as well as the expended links. The belt-fed CAR-15 was similar to the belt-fed AR-10 developed by Eugene Stoner and John Peck at ArmaLite. The Army evaluated its use as a helicopter door machine gun but rejected it, so less than 20 of the Heavy Assault Rifle M2s were made.
CAR-15 Submachine Gun
CAR-15 Submachine Gun Type Carbine Place of origin United States Specifications Weight Empty: 5.3 lb (2.40 kg) Length Buttstock extended: 28.7 in (729 mm)
Buttstock retracted: 26.0 in (660 mm)
Barrel length 10 in (254 mm) Muzzle velocity 2,650 ft/s (808 m/s)
The Model 607 CAR-15 Submachine Gun (SMG) was a compact weapon for use by special forces and vehicle crewmen. The dictionary definition of submachine gun is an automatic firearm that fires pistol-caliber cartridges. However, manufacturers such as Colt, Heckler & Koch, and Zastava Arms have referred to compact carbines as submachine guns, to emphasize their short length and to differentiate them from longer carbines.
The CAR-15 SMG was the first AR-15 made with a retractable buttstock, with its overall length being only 26 inches with the buttstock retracted. The retractable buttstock resembled a shortened version of the fixed buttstock, but a two-position latch recessed in the back allowed it to be extended and locked into position, increasing the length of pull by 2.7 inches. The barrel is too short to mount a bayonet, so the SMG had no bayonet lug.
About 50 CAR-15 SMGs were made. Most were issued to Navy SEALs and Army Special Forces, though some were also given to Army K-9 units. Since it never went into full production, CAR-15 SMGs were assembled from available spare parts. The first models were made with M16 receivers without forward assists and with shortened pistol grips from the Survival Rifle (see below). The later Model 607As were made with XM16E1 receivers with forward assists and standard pistol grips. The handguards were made from full-length rifle handguards by cutting them in half and using either the fore or aft pair, after machining the ends to fit the slip ring and handguard cap.
Because of the short barrel, the CAR-15 SMGs suffered from a loud and bright muzzle blast, and a number of muzzle devices were developed to reduce this. The SMGs were initially fitted with the standard M16 rifle's "duckbill" or three-prong flash hiders, which did not alleviate the problem. In September 1966, Colt developed a 3.5-inch long moderator that lessened the noise and muzzle flash, which also increased the weapon's reliability by increasing the amount of back pressure. However, the moderator created its own problems, such as heavy bore fouling and causing tracer bullets to wildly yaw. A 4.25-inch long moderator with six slots and an expansion chamber, which further reduced noise and flash, replaced the previous muzzle device and became standard for the SMG and the Commando series, but fouling and tracer problems persisted.
CAR-15 Survival Rifle
CAR-15 Survival Rifle Type Carbine Place of origin United States Specifications Weight Empty: 4.75 lb (2.15 kg) Length 29.0 in (737 mm) Barrel length 10 in (254 mm) Muzzle velocity 2,650 ft/s (808 m/s)
The Model 608 CAR-15 Survival Rifle was meant for use by downed aircrew. Because of the CAR-15's modular design, the Survival Rifle could be broken down into two subassemblies and stowed with four 20-round magazines in a pilot's seat pack. With only a 10-inch long barrel, the assembled weapon was 29 inches in overall length. The Survival Rifle used a fixed tubular plastic-coated aluminum buttstock and a round handguard that were not used on the other CAR-15 versions, and did not have either a forward assist or a bayonet lug. The pistol grip was chopped down, and the muzzle was equipped with either a conical flash hider or the 3.5-inch long moderator.
CAR-15 Commando (XM177/GAU-5 series)
Submachine Gun, 5.56 mm, XM177E2 Type Carbine Place of origin United States Specifications Weight Empty: 5.35 lb (2.43 kg) Length Buttstock extended: 32.5 in (826 mm)
Buttstock retracted: 29.8 in (757 mm)
Barrel length 11.5 in (292 mm) Muzzle velocity 2,750 ft/s (838 m/s)
The CAR-15 Commando was not initially part of the CAR-15 Military Weapons System, but was added in 1966 in response to the US military's desire for a shorter M16 and the Model 607 SMG's inadequacies. Colt engineer Rob Roy designed a simpler two-position telescoping tubular aluminum buttstock to replace the complicated extending triangular version. The fragile and ad hoc triangular handguards were replaced by reinforced round handguards. Each half of the round handguard was identical, simplifying logistics by not requiring a top/bottom or left/right pair. The Model 609 Commando had a forward assist, while the Model 610 Commando did not. A Model 610B with a four-position selector was available, but not used by the U.S. military. All versions were equipped with the 4.25-inch long moderator.
The Model 610 was classified as the XM177 but adopted by the Air Force as the GAU-5/A Submachine Gun (GAU = Gun, Aircraft, Unit.) The Army purchased 2,815 Model 609 CAR-15 Commandos on June 28, 1966, which were officially designated Submachine Gun, 5.56 mm, XM177E1. As part of the contract, Colt was supposed to supply each XM177E1s with seven 30-round magazines, but Colt was unable to build a reliable 30-round curved magazine that would fit in the M16 magwell, so most XM177E1s were shipped with 20-round magazines. The exception was 5th Special Forces Group, who received a total of four early 30-round magazines. Colt completed delivery of the purchased XM177E1s in March 1967.
In 1967, in response to field testing, Colt lengthened the Commando's barrel from 10 inches to 11.5 inches. The increased length reduced noise and muzzle flash, and allowed fitting of the Colt XM148 grenade launcher. A metal boss was added to the moderator for mounting of the XM148 and rifle grenades. The chambers were chrome-plated. The Commandos with the longer barrels were called the Model 629 and Model 649. The Model 629 Commando had a forward assist; the Model 649 Commando did not.
In April 1967, the Army purchased 510 Colt 629 Commandos for use by troops assigned to the Military Assistance Command, Vietnam Studies and Observations Group (MACV-SOG), and designated them XM177E2. Delivery was completed by the end of September 1967. The Air Force adopted a similar model without the forward assist feature as the GAU-5A/A. Sources debate whether or not this was a Colt Model 630 or 649. According to John Plaster and other sources, the lack of 30 round magazines continued to be problematic and SOG operators resorted to pooling their personal resources and purchasing the larger capacity magazines on the civilian U.S. market. Problems with range, accuracy, barrel fouling, and usage of tracer bullets continued to plague the XM177 series, but Colt estimated that it would take a six-month $400,000 program to do a complete ballistic and kinematic study. There were also recommendations for a 29-month $635,000 research and development program. Both recommendations were declined by the U.S. military as American ground force involvement in the Vietnam War was gradually winding down. Production of the CAR-15 Commando ended in 1970.
After the Vietnam War, Colt abandoned the CAR-15 Military Weapons System concept, but continued to develop heavy-barreled rifles, carbines, and Commandos for military use. These were marketed under the M16 or M16A1 name, while the civilian and law-enforcement semi-automatic counterparts were marketed as AR-15s.
In the mid-1970s, the Bureau of Alcohol, Tobacco, and Firearms (BATF) declared the 4.25-inch long moderator a sound suppressor. During the Carter Administration, the U.S. State Department banned the sale of sound suppressors to foreign countries. Colt therefore designed carbines without the moderator.
Colt Model 653 M16A1 Carbine
Colt AR-15 Sporter SP1 Carbine
AR-15 with scope
Type Carbine Place of origin United States Specifications Weight Empty: 5.6 lb (2.54 kg) Length Buttstock extended: 33 in (838 mm)
Buttstock retracted: 29.8 in (757 mm)
Barrel length 14.5 in (368 mm) Muzzle velocity 3,020 ft/s (920 m/s)
Rate of Fire: 650-750 RPM
In the early 1970s, Colt began development of an M16A1 carbine with a 14.5-inch long barrel. The 14.5-inch length was compatible with the existing carbine-length gas system and allowed for the mounting of a standard M16 bayonet. Despite having a longer barrel, it would not be less compact than the previous carbines. Depending on whether it had a fixed or retractable buttstock and a forward assist, Colt labeled the M16A1 carbines the Model 651, 652, 653, or 654. All models used the M16A1 birdcage flash hider. Only the Model 653 M16A1 carbine, with retractable buttstock and forward assist would be purchased in significant numbers by the U.S. military. The United States Army, Navy and Air Force, as well as the Malaysian Armed Forces, purchased Model 653s in small numbers for special operations forces or security forces.
During the Yom Kippur War, the American government sent arms and equipment, including Model 653s, to the Israeli Defense Forces as part of Operation Nickel Grass. These Model 653s, which have been called "CAR-15s" by its users, continue to be in use with the IDF today. Some of the Model 653s in Israeli service have been heavily customized over the service years, such as having the barrel replaced or chopped down in length. They have been nicknamed Mekut'zar or Mekut'zrar. They are slowly being replaced with/or revamped to M4 carbines. Colt also licensed Elisco Tools to produce the M16A1 carbine in the Philippines, who became a major user of the type, as the Model 653P.
In the early 1980s, at the request of the United States Marine Corps, Colt upgraded the M16A1 rifle, resulting in the M16A2 rifle. Among the major changes were a reinforced lower receiver, a case deflector, a birdcage flash suppressor redesigned to be a muzzle brake, and a barrel with a faster 1-in-7 twist. The faster barrel was necessitated by the switch from the 55 grain M193 bullet to the 62 grain M855 bullet. The M16A2 rifle's barrel was also thicker for the portion in front of the handguard. Colt incorporated these changes into its carbines, which it called M16A2 carbines. The Model 723 M16A2 carbine used the iron sights of the M16A1, but had a case deflector. The barrel had a 1-in-7 twist, but the thinner profile of the older M16A1 carbine's barrel. As with the Model 653, the United States military made small purchases of the Model 723 for its special operation forces.
In 1984, the United States government asked Colt to develop a carbine with maximum commonality with the issue M16A2. Colt named the carbine as the XM4. The project would eventually culminate in the official adoption of the M4 carbine in 1994.
The United Arab Emirates (U.A.E.) wished to purchase M16A2 carbines with the thicker M16A2 barrel, but still be able to mount the M203 grenade launcher. The M203 grenade launcher was designed for the thinner M16A1 barrel. A "step-cut" barrel was made, with a portion of the barrel thinned for the M203 mount. M16A2 carbines with A2 upper receivers and the step-cut barrel were designated Model 727. These are often called "Abu Dhabi" carbines, in reference to the capital of the U.A.E. The U.S. military also purchased several of these carbines prior to the official adoption of the M4.
GAU-5/A and GUU-5/P
Type Carbine Place of origin United States Specifications Muzzle velocity 2,611 ft/s (796 m/s)
Rate of Fire: 700-1000 RPM
The United States Air Force has made ad hoc upgrades to its GAU-5/As and GAU-5A/As. The barrels and moderators were replaced with the longer 14.5-inch barrel with a 1-in-12 twist, but the weapons retained their original designations. With the change to M855 cartridges, they either received 1-in-7 twist barrel or complete upper receiver assembly replacements. The GAU-5/A or GAU-5A/A markings were removed and the weapons redesignated GUU-5/P. They also retain automatic fire instead of burst.
The new designation more accurately reflected the weapon's place in the U.S. Air Force Aerospace Equipment Type Designation System (AETDS). The weapons had initially been designated in the same format as aircraft guns, being placed in the GA category (GA designating an aircraft gun, with U meaning unit, representing a complete system and not part of a kit), followed by the /A suffix meaning the system was for aircraft. GUU is the "guns, miscellaneous personal equipment" category, and the /P suffix indicating personal equipment.
M4 Commando Type Carbine Place of origin United States Specifications Weight Empty: 5.38 lb (2.44 kg) Length Buttstock extended: 30 in (760 mm)
Buttstock retracted: 26.8 in (680 mm)
Barrel length 11.5 in (290 mm) Muzzle velocity 2,611 ft/s (796 m/s)
Though Colt has focused its attention on carbines with 14.5-inch barrels and rifles with 20-inch barrels, Colt continues to make carbines with 11.5-inch barrels, which it calls Commandos. Commandos are assembled from whatever spare parts are available, so Model 733 Commandos can have A1-style upper receivers, A1-style upper receivers with case deflectors, or A2-style upper receivers, and M16A1-profile 1:7 or M16A2-profile 1:7 barrels. Depending on the specific models, current Commandos may have three-position fire control groups (safe/semi-automatic/three-round burst), or four-position having both full-automatic and burst. The Model 933 has a "flattop" receiver, with a removable carrying handle and a MIL-STD-1913 Picatinny rail. Though originally called the M16A2 Commando, Colt now markets it as the M4 Commando.
Some American special operation forces, such as Army Special Operation Groups, use the M4 Commando in a limited capacity. Marine Force Recon personnel sometimes use M4 Commandos in place of their US M9 pistols.
The Colt Commando's 11.5-inch barrel creates a substantially lower muzzle velocity and greater muzzle flash, in comparison to longer M16 carbines and rifles. The lower muzzle velocity may reduce wounding effects. In 2005, Colt came out with a semi auto only version of the 733. The designation of this rifle is the 6933.
USAF Combat Control Team (CCT) member with GAU-5A/A. The GAU-5A/A can be distinguished from the GAU-5/A by the 1.5 inches of barrel between the moderator and the front sight block.
The Malaysian Army operator (left) holding the M16 carbine.
A United States Navy SEAL handling his CAR-15
- ^ Dockery, 1997. pg. 133
- ^ Dockery, 1997. pg. 139
- ^ a b c d Ezell, 1988. p. 401
- ^ Dockery, 1997. pg. 143
- ^ Plaster, 2004. p. 216
- ^ Dockery, 1997. pg. 165
- ^ "Designations Of U.S. Aeronautical and Support Equipment" – www.designation-systems.net
- ^ "M4 Commando" – Colt Weapon Systems
- ^ "Strong Men Armed: The Marine Corps 1st Force Reconnaissance Company" – ForceRecon.com
- ^ The AR15.com Ammo-Oracle
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- "Colt XM177 5.56mm Submachine Gun" – Warboats.org
- U.S. SUBMACHINE GUN XM177 – Springfield Armory Collection
- Retro Black Rifle.com – Guide to AR10/AR15/M16 Rifles up to the mid-1980s
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