User:Pettifogger/CAR-15

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. Due to their compact size, the short-lengthed Colt Commando and XM177 series were the only members to see usage beyond 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, 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 M16 and AR-15 variants, usually a carbine.

History
Starting in 1965, Colt attempted to market the M16 rifle as a single 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. Thus, a military could use a M16 as a rifle, a heavy barreled assault rifle, a carbine, a submachine gun, and 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 tool-room prototypes and never entered full-scale production. As a result, wide variation due to experimentation exists within each model. The United States military only made significant purchases of the Rifle and Commando, so Colt abandoned the CAR-15 family concept. The CAR-15 Rifle was already identified by people as the M16 or AR-15, so many associated the CAR-15 name with only the short-barreled Submachine Gun and Commando models. Because of that, CAR-15 has been used to describe any M16-based carbine, even if the particular weapon is not officially named thus.

CAR-15 Rifle
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, though the United States military had already committed to purchases before Colt had 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
The Model 605A CAR-15 Carbine was a shortened version for situations where length could be a problem, such as stowage aboard vehicles. The only significant change from the M16 rifle was that the barrel was shortened to 15 inches in length, so that it ended just fore of the front sight triangle. Because of the lack of visible barrel, a standard bayonet could not be attached so the carbines did not have bayonet lugs. One prototype used a shorter handguard and a 16-inch long barrel. The Model 605B had no forward assist, but had a four-way selector switch so that a user may select safe, semi-automatic, three-round burst, or full automatic. Instead of three-round burst, the burst cam could be modified to two-round or six-round burst. The 4-position selector was developed by Foster Sturtevant in December 1966. As early as 1962, United States Navy SEALs were using the CAR-15 Carbine. The civilian Bushmaster Dissipator is a modern incarnation of the CAR-15 carbine.

CAR-15 Heavy Assault Rifle
The Model 606 CAR-15 Heavy Assault Rifle used a heavy barrel (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 a Colt bipod, a M14 rifle M2 bipod, or a modified BAR bipod.

CAR-15 Heavy Assault Rifle M1
The CAR-15 Heavy Assault Rifle M1 used 20-round M16 box magazines, which limited its ability to provide a sustained rate of 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-way selector, adding a burst capability. The Army purchased less than 200 Heavy Assault Rifle M1s for use in the Small Arms Weapons Systems (SAWS) tests in 1965.

CAR-15 Heavy Assault Rifle M2
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 a belt-fed AR-10 developed by Eugene Stoner and John Peck at Armalite. The Army evaluated their use as helicopter door armament, but rejected it, so less than 20 of the Heavy Assault Rifle M2s were made. John Ciener manufactures a modern-day belt-fed conversion for current M16s similar to the Heavy Assault Rifle M2.

CAR-15 Submachine Gun
The Model 607 CAR-15 Submachine Gun (SMG) was a compact weapon for use among special forces and vehicle crew. 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 the buttstock retracted, it was only 26 inches long. 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 SMGs were made with M16 receivers without forward assists and with shortened pistol grips from the Survival Rifle. The later ones, labeled Model 607As, were made with XM16E1 receivers with forward assists and standard pistol grips. The handguards were made from full-length rifle handguards by chopping them in half and using either the fore or aft pair. The ends would then be machined to fit the slip ring and handguard cap.

Because of the short barrel, the CAR-15 SMGs suffered from a loud and bright muzzle flash. So a number of muzzle devices were tried on the CAR-15 SMG. 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 made a 3.5-inch long moderator that lessened the noise and muzzle flash. It also aided reliability by increasing the amount of back pressure. However, it created problems such as heavy barrel coppering 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, would replace the previous muzzle device and become standard for the SMG and the Commando series, but fouling and tracer problems persisted.

CAR-15 Survival Rifle
The Model 608 CAR-15 Survival Rifle was meant for use among downed aircrew. Because of the AR-15's takedown feature, the CAR-15 Survival Rifle could be split in two 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 CAR-15 Survival Rifle used a fixed tubular plastic-coated aluminum buttstock and a round handguard that were not used on the other CAR-15 versions. It did not have a forward assist or a bayonet lug. The pistol grip was chopped down. The barrel muzzle ended in either a conical flash hider or the 3.5-inch long moderator.

CAR-15 Commando aka XM177 series
The CAR-15 Commando was not an initial member of the CAR-15 Military Weapons System, but added in 1966 in response to the US military's desire for a shorter M16 and the Model 607 SMG's inadequacies. Rob Roy designed a simpler two-position telescoping tubular aluminum buttstock to replace the complicated extending triangular buttstock. 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; The Model 610 Commando did not. A Model 610B with a four-way selector was available, but not used by the US military. They all had 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 is short for Gun, Automatic, Unit. The Army purchased 2,815 Model 609 CAR-15 Commandos on June 28, 1966. They were officially designated Submachine Gun, 5.56mm, 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 by 1.5 inches to a total barrel length of 11.5 inches. The length increase further 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 with the MACV-SOG, and designated them as the XM177E2. Delivery was completed by the end of September 1967. The Air Force adopted the Model 649 Commando as the GAU-5A/A. 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 were ignored as the Vietnam War wound down. Production of the CAR-15 Commando ended in 1970.

Post-Vietnam
After the Vietnam War, Colt had abandoned the CAR-15 Military Weapons System concept, but continued to develop heavy barreled rifles, carbines, and Commandos except they were marketed under the M16 or M16A1 name. However, because most people were only exposed to the CAR-15 family through the SMG and Commandos, any AR-15 or M16 carbine was often called a CAR-15.

In the mid-70s, the Bureau of Alcohol, Tobacco, and Firearms (BATF) declared the 4.25-inch long moderator a sound suppressor. During the Carter Administration, the State Department banned sale of sound suppressors to foreign countries. Hence, Colt designed carbines without the moderator.

Colt Model 653 M16A1 carbine
In the early 1970s, Colt developed a 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 buttstock or retractable and a forward assist or not, Colt labeled the M16A1 carbines the Model 651, 652, 653, or 654. They all used the M16A1 birdcage flash hider. Only the Model 653 M16A1 carbine, with retractable buttstock and forward assist would have significant purchases. The United States Air Force, Army and Navy all 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, 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 M4 carbines.

Colt licensed Elisco Tools to produce the M16A1 carbine in the Phillipines, as the Model 653P. These Model 653Ps would be used anachronistically in the movie Platoon, which was filmed in the Phillipines.

M4 Carbine
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 field 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.

The United Arab Emirates wanted 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; a portion of the barrel was thinned out just for the M203 mount. M16A2 carbines with A2 upper receivers and the step-cut barrel were the Model 727. They're often called the "Abu Dhabi" carbines, in reference to the capital of the U.A.E. The US military made select purchase of these carbines as well.

In 1984, the United States government asked Colt to develop a carbine. Based on the work of the Model 723 and 727, the project would eventually culminate in the M4 carbine, officially adopted in 1993.

Independent of the M4 program, in 1983, Diemaco developed a carbine similar to the Model 723, the C8 carbine for use by the Canadian Forces. The original C8s were built by Colt as the Model 725.

GUU-5/P
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 they still retained their designations. With the change to M855 cartridges, they either received 1-in-7 twist barrel or upper receiver replacements. The GAU-5/A or GAU-5A/A markings were scratched out and the weapons were redesignated GUU-5/P. The Air Force has changed its classification system so that GAU is Gun, Airborne, Unit. The A suffix is for a fixed aircraft installation. GUU is Gun, Miscellaneous, Unit. The P suffix is for individual-carried equipment.

Colt Commando
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 Commados 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 fire control groups that are fully automatic, three-round burst, or four-way having both automatic and burst. They may also have a "flattop" receiver, which has removable carrying handle and a MIL-STD-1913 rail. Though originally called the M16A2 Commando, Colt now markets them as M4 Commandos. 

Some American special operation forces, such as Marine Force Recon use the Colt Commando in a limited capacity. However, recently, the Mk 18 Mod 0, which has a 10.3-inch barrel, has taken the role of compact carbine in the American military.

The Colt Commando's 11.5-inch barrel creates a substantially lower muzzle velocity and greater muzzle flash, in comparison to longer M16 carbines. The lower muzzle velocity may reduce any wounding effects. 

Summary table
Terms
 * Model number
 * Bold model numbers were weapons used by US military
 * Italic model numbers are weapons for commercial or export sale
 * Name
 * Bold names are official US Military designations
 * Stock
 * Until 1985, Colt used an aluminum retractable stock. Colt replaced it with a nylon stock that was identical in appearance. In 2002, the nylon stock was replaced with a new design by Picatinny Arsenal engineer Lily Ko that had reinforced ribs, an angled buttplate, and a rear sling swivel.


 * A1: Fixed stock as used on M16 and M16A1. May or may not have a trapdoor to store a cleaning kit.
 * A2: Improved stock used on M16A2. Longer by 5/8".
 * 2-pos: The receiver extension has two positions.
 * 4-pos: The receiver extension has four positions
 * 607: The CAR-15 SMG had unique 2-position sliding stock that resembled a shortened fixed buttstock
 * 608: The CAR-15 Survival Rifle had a unique fixed tubular buttstock.
 * Fire control
 * Auto: The selector is safe-semi-auto
 * Burst: The selector is safe-semi-burst
 * 4-way: The selector is safe-semi-burst-auto
 * Rear sight
 * A1 : "Field sights" in which the rear sight is only adjustable for windage
 * A2 : Rear sight adjustable for both windage and elevation
 * Flattop : Carrying handle and rear sight has been replaced with a MIL-STD-1913 rail
 * Barrel profile
 * Pencil: Original barrel profile where barrel diameter is between 0.675 and 0.575 inches.
 * Government: Barrel profile for which the portion of the barrel in front of handguards is thickened to 0.715 inches
 * HBAR: A barrel that in some portion is thicker than government-profile, usually underneath the handguards
 * M4: Government barrel profile with small portion reduced to 0.575 inches to mount M203 grenade launcher
 * SOCOM: M4 barrel with portion under handguard thickened for sustained automatic fire
 * Barrel twist
 * 1:12: 1 right hand twist every 12 inches (305 mm)
 * 1:7: 1 right hand twist every 7 inches (177.8 mm)
 * Handguards
 * Triangular: Triangular rifle handguards
 * 607: The CAR-15 SMG had shortened triangular handguards
 * 608: The CAR-15 Survival Rifle had a smooth round handguard not used on any other model.
 * Round: Round rifle handguards
 * CAR: Round carbine handguards
 * M4: Oval carbine handguards with double heatshields
 * Muzzle device
 * Duckbill: Original three-prong flash hider
 * Three-prong: Beefed-up three-prong flash hider
 * Birdcage: Birdcage flash hider
 * Compensator: Birdcage flash hider with bottom slots closed off to act as muzzle compensator
 * Moderator: Either the 3.5-inch or 4.5-inch moderator

Colt models

Non-Colt models