CAR-15
The Colt Automatic Rifle-15 or CAR-15 is a family of M16 rifle–based firearms marketed by Colt in the 1960s and early 1970s. However, the term "CAR-15" is most commonly associated with the Colt Commando ; these select-fire carbines have ultrashort and barrels with over-sized flash suppressors.
Etymology
The CAR-15 name was an attempt to re-associate the AR-15 name with Colt, since the “AR” designation stood for “Armalite Rifle", the original manufacturer of the ArmaLite AR-15. Colt later abandoned the CAR-15 concept, but continued to make carbine variations, using the "M16" brand for select-fire models and the "Colt AR-15" brand for semi-automatic models. However, in present usage, "CAR-15" is the generic name for all carbine-length variants made before the M4 carbine.History
After Colt's Patent Firearms Manufacturing Company purchase of the rights and intellectual property to the AR-10 and AR-15 rifles from Armalite in late 1959, Colt embarked on a research and development program to create variations of the AR platform that evolved into the CAR-15 family of firearms. The focus of the CAR-15 R&D was to develop five different variants of the existing AR-15 in addition to a 40mm grenade launcher. The five firearms developed were a submachine gun, a carbine, a heavy barrel magazine-fed squad automatic weapon, a belt-fed machine gun, and a compact survival rifle. Only the SMG generated any interest with the U.S. Army and "Aside from limited purchases of 100-150 M-1 heavy assault rifles for trials during the upcoming SAWS program, the military was cool to most of Colt's CAR-15 Military Weapons System, and only a handful of carbines, M-2 belt-fed assault rifles and survival rifles were ever produced. However, the short-barreled submachine gun and the 40mm grenade launcher attachment did undergo considerable further development."The CAR-15 program started in earnest in 1964 with samples of the SMG Model 607 being submitted to the U.S. Army for evaluation. Starting in May 1965, Colt attempted to market the M16 rifle and its variants developed under the CAR-15 program to commercial markets and markets outside the United States as a modular weapon system. By using various upper assemblies, buttstocks, and pistol grips, the weapon could be configured as an assault rifle, a carbine, a submachine gun, an open-bolt squad automatic weapon, a belt-fed light machine gun, or a survival rifle. There was a second belt-fed machine gun developed under the CAR-15 program called the CMG-1, CMG-2, and CMG-3 in 7.62 NATO that was not based on the existing AR-15/M16 design. However, the U.S. military only made significant purchases of the existing M16 rifle and the SMG model, later called the Commando versions, so Colt abandoned the CAR-15 family concept. The "CAR-15 Rifle" was already identified by most users as the M16 rifle, and "CAR-15" was similarly associated with the short-barreled Colt 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 this.
Colt Automatic Rifle-15 family
CAR-15 Rifle (M16 rifle)
Beginning in 1961 under ARPA's Project Agile, Colt provided approximately 1,000 AR-15s for evaluation to the U.S. Government in southeast Asia. Colt was eventually awarded their first contract to supply the U.S. Army and U.S. Air Force with the M16 in November, 1963. 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 a stuck bolt.CAR-15 Heavy Assault Rifle M1 (Model 606)
The CAR-15 Heavy Assault Rifle M1 was a heavy-barreled version of the standard CAR-15 with a bipod attachment, intended for use as a Squad Automatic Weapon. It was designed to feed from the same detachable box magazine used for the M16. Approximately 100-150 were produced by Colt for evaluation by the U.S. Army during the SAWS program in 1965. Colt continued attempts to market the HBAR M16A1 as the Model 621 through the late 1970s without success and only a few dozen were manufactured. Colt did eventually produce a heavy barrel civilian market semi-automatic AR-15 beginning in the late 1980s based on the M16A2 called the AR-15 HBAR that was a commercial success.CAR-15 Heavy Assault Rifle M2
The CAR-15 Heavy Assault Rifle M2 was a belt-fed conversion of the standard CAR-15, with a heavy barrel and bipod attachment. It was made in prototype form only and saw no sales. The CAR-15 Heavy Assault Rifle M2 was not related to the CMG-1, CMG-2, or CMG-3 belt fed machine guns.CAR-15 Carbine (Model 605)
The Model 605 CAR-15 Carbine was a shortened version of Colt's M16E1/M16A1 for situations where longer weapons could be unwieldy, such as inside armored vehicles, ships/boats, or helicopters. There were only a very small number of known prototypes of the carbine made sometime after the 1963 award of the first contract to Colt for the delivery of the M16 and M16E1. The first prototype was essentially an M16E1/M16A1 rifle with 5 inches of the barrel removed resulting is a barrel in length, so that it ended just forward of the front sight base. Because of the shorter barrel and no space to attach a bayonet, the bayonet mounting lugs removed. Due to the shortened barrel with the gas port intersecting the barrel bore near the muzzle, the gas port diameter was opened up to match the internal diameter of the gas tube at 0.110 inches.A second prototype used a custom profile barrel with the gas port and front sight base/gas block moved back approximately 2.5 inches to improve reliability. A standard M16 handguard had 2.5 inches cut off the back to fit the shortened barrel/gas system, and a custom adapter fabricated to retain the modified handguard in the existing retainer ring surrounding the barrel nut. As an added benefit from the relocated front sight/gas block a bayonet was able to be fitted. This gas system is arguably the first use of what is called today as a "mid-length" gas system since it falls between the 12 in gas system of the rifle and the 7 inch gas system used in the SMG variants.
Because of the issues with reliable cycling caused by the shortened barrel, Colt experimented with buffers and low mass bolt carriers during the development of the carbine and SMG versions of the CAR-15. The only two known versions of the Model 605 prototypes used a modified lower receiver assembly that appears to use an early M16 Model 603 type forging without the "fence" surrounding the magazine release button. The modified lower receiver incorporated a four-position selector switch 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 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.
The Model 605 prototypes used what appeared to be an M16E1/M16A1 upper receiver forging but with the forward assist deleted and the hump mostly machined off. Both prototypes used the standard rifle-length buttstock.
Despite the failure of Colt's CAR-15 program to produce a successful carbine variant, in the mid 1990s Bushmaster manufactured a similar firearm based on the semi-automatic civilian market M16A2. The Bushmaster XM-15 Dissipatior used a 16 inch barrel and standard rifle length handguard and front sight location, but differed significantly in that it used a M4 length gas system with a gas block separate from the front sight block hidden under the handguard. In the early 2020s, Brownells manufactured their BRN-605, a "retro-rifle" clone of the first prototype CAR-15 carbine but used a 16 inch barrel instead of 15 inch, but the Brownells clone used the same rifle length gas system as the first Model 605 prototype.
CAR-15 Submachine Gun (Model 607)
As early as 1964, United States Navy SEALs were testing prototypes of what would become the Model 607 SMG. Colt's manufactured approximately 50 of these for evaluation. Most were issued to Navy SEALs and Army Special Forces, though some were also given to Army K-9 units.In 1965, Colt introduced the Model 607 Submachine Gun. This was the first AR-15 made with a retractable buttstock and was as a product of the development of Colt's SMG prototypes. Its overall length was only with the buttstock collapsed. 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. The barrel is too short to mount a bayonet, so the SMG had no bayonet lug. It 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 Model 607 never went into production, however the limited success during the prototype development resulted in further interest by the U.S. Army and U.S Air Force. The first models were made with M16 receivers without forward assists and with shortened pistol grips from the Survival Rifle. The later Model 607A was made with XM16E1 receiver with forward assist and standard pistol grip. The handguard was made from full-length rifle handguard by cutting it 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 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 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.