Colt Commando

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US Colt Commando
Technical Summary

Caliber:

5.56 x 45 mm

Firearm action:

Gas-operated, rotating bolt

Magazine:

30-round detachable box

Mass:

2.44 kg (5.38 lb) empty
2.89 kg (6.38 lb) w/ 30 rounds

Overall length:

760 mm (30 in)

Barrel length:

290 mm (11.5 in)

Rate of fire:

700–1000 rounds/min

Effective range:

200 m (Source)

Muzzle velocity:

2611 ft/s (796 m/s)

The Colt Commando (also referred to as CAR-15 or XM177) is a general name for a wide array of shortened and modified AR-15/M16 firearms developed primarily in the late 20th century. They are a family of gas-operated, locking bolt 5.56 x 45 mm carbines, and were developed and produced by Colt manufacturing, mainly for U.S. Special Forces, starting in the 1960s.

The moniker "Commando" has been used to describe Colt’s ultra-short carbine variants, as well as, "pre-A2 configuration" or "pre-M4" in general. The first weapon in this ultra-short category began production in 1966/7 for Special Operations units during the Vietnam war. By the end of the conflict, it had been used by members of various elite units, and had been given a slew of official and semi-official designations, in addition to the informal names it received in the field. The CAR-15/Commando/XM177 family has one of the most complicated array of variants and names among US service firearms. Popular monikers for the family, such as 'CAR-15', or 'XM-177', have much more complicated meanings when talking about actual, specific, versions of the family.

In the mid-1960's Colt created and sold an ultra-short carbine variant of the M16 for the US Army. It looked much like a miniaturized M16A1 rifle, and featured a retracting buttstock modeled after the full rifle stock. With a 10 in (254 mm) barrel, muzzle blast soon became a major issue, and while the initial variants were equipped with the same flash hiders as A1 rifles, special "moderators" were quickly created.

The current iteration – the M16A2 Commando – is similar in design and has many interoperable components with the M4 Carbine and the M16A2 Rifle; the Commando being the shortest and most compact of the three weapons

1 Early models & naming
2 The XM177 and the GAU-5/A
3 Late 1970s and 1980s
4 Related models
5 Criticisms
6 See also
7 External links

[edit] Early models & naming

The original "Commando" was created when Colt began developing the AR-15 pattern, newly acquired from Armalite. The need for a shorter handier weapon had been expressed by a number of forces engaged in the expanding conflict in South East Asia in the mid 1960s, and Colt responded with an ultra-short variant as part of its new CAR-15 family, the Model 607 CAR-15 Commando Model Submachine Gun. Note that calling it a submachine gun was a new trend in submachine gun (SMG) naming, as previous SMGs were all chambered for pistol, rather than rifle ammunition. Classifying very short assault rifles as SMGs has been common practice in a number of firearm books, though it is not universally accepted. By the time the contract for rifles was signed by the Army in 1966, CAR-15 SMG, or just CAR-15, and 'Commando' were the two main names in use for the Colt Model 607. In early field manuals, the name Submachine Gun, 5.56 mm, CAR-15 can be found. By 1967 and later a slew of new variants would be developed, and were given various designations by the US Army and the USAF.

In January 1967 the family got a type classification- XM177/E1 submachine guns, which featured improvements on the earlier models. More variants would get even more names using Air Force nomenclature ('GAU prefix'). The CAR-15 Survival Rifle, which differed from the basic CAR-15 Commando, was a version Colt developed for the Air Force, but they did not accept it.

See also: CAR-15

Troops in the field ended up simply referring to it as CAR-15, rather than CAR-15 SMG, or Colt Commando. While CAR-15, or Colt Automatic Rifle-15, was to be used for an entire family of Colt patterned AR-15 type weapons including 2 rifles, 2 Heavy Barreled rifles or HBARs, a 16 in (406 mm) carbine, and the ultra-short 10 in (254 mm) gun, it quickly fell by the wayside. CAR-15 has since been used to describe later models, such as A1 configured or pre-M4 type carbines. CAR-15 and Colt Commando are in the common lexicon for these breed of weapons, though care must be taken when talking about specific variants. Really, pre-XM177 models are those best described with CAR-15, and even then it should be noted that they were the "Submachine Gun" members of that family. CAR-15 has also persisted in the civilian market as a term for semi-automatic carbines of the AR-15/M16 pattern.

The choice between CAR-15 (or CAR-15 submachine gun), XM177, Colt Commando, or CAR-15 SMG, varies between sources when trying to describe the whole family of variants. Commando is probably the most accurate when talking about the family as a whole, as this has been the a major part of Colt factory nomenclature (Colt Defense offers a 'M4 Commando' even in 2005 [1]. However, when dealing in specifics, specific variant models should be specified as their differences may be slight, but are important in understanding development.

The 16" carbine, the Colt Model 605, was built in 3 variants, one without the forward assist, one with, and one with a four-position burst function. This function found its way onto a variant of the ultra-short "Commando" family, as well as, an HBAR in addition to the 605. A small number of 605s were procured for the US Navy SEALs and used by them in South East Asia. Despite what was regarded to be a generally positive response, development progressed on 607 patterned weapons.

The Model 607 itself looks much like a miniaturized M16, featuring short older style triangular handguards and a buttstock that while retractable was similar in shape to that of the full size rifles. These weapons featured a 10" barrel and were initially fitted with the same flash hiders as the parent rifles. The excessive blast from the short barrel quickly made development of a specific "moderator" necessary and a 3.5" version was fitted to later models. Later on, remaining Model 607s in service would also be found fitted with 4.5" moderators from XM177/GAU-5s described later. Early versions of this weapon were also not fitted with the forward assist feature, like the M16 in service with the USAF. Later versions and the later factory designated 607A had this feature, similar to the US Army's M16A1s.

In addition to the 607 Colt manufactured the Model 608, which was a special survival rifle prototype made specifically for the US Air Force, but never adopted. Only 10 were believed to have been made.

[edit] The XM177 and the GAU-5/A

With the initial success of the 607 idea, Colt refined the pattern and created 3 additional guns, the 609, 610, and 610B. The most important features of these guns are the revised retracting stocks (similar in style to the stocks commonly found on M4 type rifles), originally cast out of aluminum, and short round handguards to help with the issues of the barrel becoming extremely hot during prolonged firing. These weapons also had 10 in (254 mm) barrels and were originally fitted with the 3.5 in (89 mm) moderators designed for the 607. A 4.5 in (114 mm) moderator was eventually created for these weapons. The 609 had a forward assist for the bolt, but neither of the 610s did. The Air Force maintained that it was an unnecessary addition that complicated the weapon, and both these guns and the M16 rifles purchased by them lacked the feature. The US Army designated the 609 the XM177E1 and the 610 as the XM177. The US Air Force designated the 610 the GAU-5/A, and it is believed received a small number of 610Bs for testing. The B stands for burst, and these featured Colt’s original four-position (Safe-Semi-Full-3RB) selector.

After fielding it, improvements were suggested, to which Colt answered with the revised Model 629 and Model 630, in which the barrel was lengthen to 11.5 inches (292 mm), which featured a barrel ring for launching rifle grenades. As the use of such weapons in the US Army declined, the ring was retained for attaching the XM148 grenade launcher. The US Army designated the 629 the XM177E2, while the US Air Force purchased the Colt model 630 (no forward assist) and it was classified GAU-5A/A. The US Air Force also received a number of "hand-me-down" Colt 629s from the US Army at some time, and it is believed that these weapons might have been designated GAU-5A/B, B/A, might have been incorporated into existing stocks of GAU-5A/As, cannibalised for parts, or simply left undesignated.

AR-15-related firearm articles:

AR-10, AR-15
M16/A1/A2/A3/A4
M4/A1 Carbine
Diemaco C7, C8
Colt Commando, XM177, CAR-15
M231 FPW
SDM-R, SAM-R
Mark 11 'SWS'
Mark 12 'SPR'
SEAL Recon Rifle
Mark 18 'CQBR'
Ares Shrike
La France M16K
KAC SR-25

Colt eventually went on to improve the basic "Commando" design in the early 1970s. The barrel was lengthened to 14.5 inches (368 mm). This barrel length allowed the usage of the M7 bayonet, and with the decision by the US administration in the late 1970s to ban the sale of sound suppression equipment abroad (the previous "XM" moderators had been classified by the BATF as sound suppressors, despite the general ridiculousness of calling them that), these weapons were fitted with the standard "birdcage" flash suppressor used on A1-type rifles. This was done to allow exportation of these weapons under the Arms Export Act of 1976, which banned the export of sound suppressors. Colt produced a number of carbine models, but the most prominent was the Colt 653. The US Army and US Navy procured some in small numbers for SOF units, but did not officially adopt it. The 653 appeared in 1973, too late to see use by US forces in South East Asia.

[edit] Late 1970s and 1980s

One of the largest end users of Colt 653s was Israel, who imported a large number just in time for the Yom Kippur War. In the last decade or so, these weapons have been extensively modified, bringing them up to a pseudo-M4 standard. These weapons have had their stock tubes modified to allow for six positions instead of the original 2 or 4, and have A2 style pistol grips, as well as, M4 profile barrels. The Israeli Defense Forces (IDF) are currently phasing these out in favor true M4/A1 carbines. Elisco Tools in the Philippines also acquired a license to produce the 653 locally, with Colt giving it the designation 653P.

The US Air Force has done a number of similar in-house upgrades and modifications to their old GAU-5 carbines, starting with simple rebarrels of 10 and 11.5 in (254 and 292 mm) guns with 14.5 in (368 mm) A1 profile barrels. It has been said that these weapons were designated GAU-5/P but no official USAF source mentions this name. It is more likely that these weapons either retained the designation of the parent weapons, went undesignated, or were designated GUU-5/P like later conversions. Also, weapons rebarreled with M4 profile barrels or with their entire upper receivers replaced with M4A1 style M1913 rail "flat top" upper receivers. Weapons in either of these configurations have been designated GUU-5/P.

These "A1" variants were used until the mid-1980s when the M16A2 and the new M855 FMJ and M856 Tracer rounds were adopted. Colt began to develop a number of carbines with the same new rifling twist, 1:7 in (178 mm) as the M16A2, designed to fire these new rounds. While the US purchased a number of Colt 720s (essentially M16A2 carbines) for testing, other countries provided the initial impetus, with the Canadian firm of Diemaco (recently purchased by Colt to provide a certain level of irony) even license producing the Colt Model 725 as the C8.

Colt also updated the original ultra-short "Commando" and released the Model 733 and Model 735. These guns again feature an 11.5 in (292 mm) barrel. The difference between the 733 and the 735 is primarily in that the 733 is Safe-Semi-Full (S-1-F) and the 735 is Safe-Semi-Burst (S-1-3). Early 733s also had A1 style rear sights. Colt eventually released variants of both these guns with M1913 rail "Flat Top" upper receivers, as the 933 and the 935 respectively.

The M16A2 Commando is similar in design and has many interoperable components with the M4 Carbine and the M16 Rifle; the Commando being the shortest and most compact of the three weapons. The M4 for all intents and purposes is identical to A1 style carbines, with the exception of the A2-style rear sights and pistol grip, upgraded stock, upgraded handguards, and extended feed ramps in the breach, along with its distinct notched barrel profile, for mounting the M203/A1 grenade launcher.

[edit] Related models

Colt model or origin	Army designation	Air Force designation	Barrel	Handguard type	Buttstock type	Pistol grip type	Lower receiver type	Upper receiver type	Rear sight type	Muzzle device	Forward assist?	Case deflector?	Bayonet lug?	Trigger pack
605	N/A	N/A	16 in (406 mm) A1 profile	Full-length Triangular	Fixed A1	A1	A1	A1	A1	Type 2 Duckbill flash hider	No	No	No	S-1-F
605A	N/A	N/A	16 in (406 mm) A1 profile	Full-length Triangular	Fixed A1	A1	A1	A1	A1	Type 2 Duckbill flash hider	Yes	No	No	S-1-F
605B	N/A	N/A	16 in (406 mm) A1 profile	Full-length Triangular	Fixed A1	A1	A1	A1	A1	Type 2 Duckbill flash hider	No	No	No	S-1-F-3
607	N/A	N/A	10 in (254 mm) A1 profile	Short Triangular	Generation 1 Retractable	A1 or shortened (vertically) A1	A1	A1	A1	Type 2 Duckbill flash hider or 3.5 in (90 mm) "Moderator"	No (Early) or Yes (Late)	No	No	S-1-F
607A	N/A	N/A	10 in (254 mm) A1 profile	Short Triangular	Generation 1 Retractable	A1 or shortened (vertically) A1	A1	A1	A1	3.5 in (90 mm) "Moderator" or 4.5 in (114 mm) "Moderator"	Yes	No	No	S-1-F
608	N/A	N/A	10 in (254 mm) A1 profile	Short Round Nonribbed	Fixed length Tubular	A1 or shortened (vertically) A1	A1	A1	A1	3.5 in (90 mm) "Moderator" or conical flash hider	No	No	No	S-1-F
609	XM177E1	N/A	10 in (254 mm) A1 profile	Short Ribbed	Generation 2 Retractable	A1	A1	A1	A1	4.5 in (114 mm) "Moderator"	Yes	No	No	S-1-F
610	XM177	GAU-5/A	10 in (254 mm) A1 profile	Short Ribbed	Generation 2	A1	A1	A1	A1	4.5 in (114 mm) "Moderator"	No	No	No	S-1-F
610B	N/A	N/A	10 in (254 mm) A1 profile	Short Ribbed	Generation 2 Retractable	A1	A1	A1	A1	4.5 in (114 mm) "Moderator"	No	No	No	S-1-F-3
629	XM177E2	N/A, retaining the name of the parent rifle, or possibly GAU-5A/B or B/A	11.5" A1 Profile	Short Ribbed	Generation 2 Retractable	A1	A1	A1	A1	4.5 in (114 mm) "Moderator"	Yes	No	No	S-1-F
630	N/A	GAU-5A/A	11.5" A1 Profile	Short Ribbed	Generation 2 Retractable	A1	A1	A1	A1	4.5" "Moderator"	No	No	No	S-1-F
653/653P	N/A	N/A	14.5 in (368 mm) A1 Profile	Short Ribbed	Generation 3 Retractable	A1	A1	A1	A1	M16A1-style flashhider	Yes	No	Yes	S-1-F
USAF Upgrade	N/A	GUU-5/P	14.5" A1 profile	Short Ribbed	Generation 2 or 3 Retractable	A1	A1	A1	A1	M16A1-style flashhider	No	No	No	S-1-F
USAF Upgrade (Rebarrel Only)	N/A	GUU-5/P	14.5" M4 profile	Short Ribbed	Generation 2 or 3 Retractable	A1	A1	A1	A1	M16A2-style flashhider	No	No	No	S-1-F
USAF Upgrade (Reupper)	N/A	GUU-5/P	14.5" M4 profile	M4 Type	Generation 2 or 3 Retractable	A1	A1	A2 or Flat Top	A2	M16A2-style flashhider	Yes	Yes	Yes	S-1-F
Israeli Mekut'zar	N/A	N/A	14.5" M4 Profile	Short Ribbed	Modified Generation 3 Retractable	A1	A1	A1	A2	M16A2-style flashhider	Yes	Yes	Yes	S-1-F
Israeli Mekut'zrar	N/A	N/A	Variable A1 Profile, 9" average	Short Ribbed	Generation 3 Retractable	A1	A1	A1	A2	Custom IDF Compensator	Yes	Yes	Yes (though unusable)	S-1-F
725	N/A	N/A	14.5" A1 Profile	Short Ribbed	Genreration 3/4 Retractable	A2	A2	A2	A2	M16A2 flashhider	Yes	Yes	Yes	S-1-F
727	N/A	N/A	14.5" A2 M4 Profile	Short Ribbed	Generation 4 Retractable	A2	A2	A2	A2	M16A2 flashhider	Yes	Yes	Yes	S-1-F
733	N/A	N/A	11.5" A1 (Early) or A2 (Late) Profile	Short Ribbed	Generation 3 or 4 Retractable	A2	A2	A2	A1 (Early) or A2 (Late)	M16A2-style flashhider	Yes	Yes	No	S-1-F
733A/735	N/A	N/A	11.5" A1 (Early) or A2 (Late) Profile	Short Ribbed	Generation 3 or 4 Retractable	A2	A2	A2	A1 (733A) or A2 (735)	M16A2-style flashhider	Yes	Yes	No	S-1-3
738	N/A	N/A	11.5" A2 Profile	Short Ribbed	Generation 4 Retractable	A2	A2	A2	A2	M16A2-style flashhider	Yes	Yes	No	S-1-3-F
933	N/A	N/A	11.5" A2 Profile	Short Ribbed	Generation 4 Retractable	A2	Flat Top	A2	N/A	M16A2-style flashhider	Yes	Yes	No	S-1-F
935	N/A	N/A	11.5" A2 Profile	Short Ribbed	Generation 4 Retractable	A2	Flat Top	A2	N/A	M16A2-style flashhider	Yes	Yes	No	S-1-3
938	N/A	N/A	11.5" A2 Profile	Short Ribbed	Generation 4 Retractable	A2	Flat Top	A2	N/A	M16A2-style flashhider	Yes	Yes	No	S-1-3-F

[edit] Criticisms

The Colt Commando shorter-barrel models are often criticized for its barrel length, which reduce muzzle velocity, and generates excessive muzzle flash.

Muzzle velocity drop can be seen from this table, adopted from testing by Bushmaster Firearms, Inc., an M16 and AR-15 rifle manufacturer. The testing used a commercial round similar to the old M193 55-grain military round, and the military 62-grain SS109 NATO standard.

M16-series barrel length effects on muzzle velocity
Barrel length	Velocity (55 gr)	Energy (55 gr)	Velocity (62 gr)	Energy (62 gr)
10 in	2,739 ft/s	916 ft·lbf	2,627 ft/s	950 ft·lbf
11.5 in	2,872 ft/s	1,107 ft·lbf	2,738 ft/s	1,032 ft·lbf
14.5 in	3,064 ft/s	1,146 ft·lbf	2,907 ft/s	1,163 ft·lbf
16 in	3,132 ft/s	1,198 ft·lbf	2,989 ft/s	1,230 ft·lbf
20 in	3,259 ft/s	1,297 ft·lbf	3,095 ft/s	1,318 ft·lbf

Adopted from: [2]

The normal trajectory standard, fired from 20-inch barrel M16 rifles, is as follows (adopted from 5.56 mm (.223) PARAMILITARY AMMUNITION in Rifle Magazine, January/February, 1988, John Schaefer).

M16-series barrel length effects on muzzle velocity
Range	Velocity (55 gr M193)	Velocity (62 gr SS109)
0 m	3,200 ft/s	3,100 ft/s
100 m	2,774 ft/s	2,751 ft/s
200 m	2,374 ft/s	2,420 ft/s
300 m	2,012 ft/s	2,115 ft/s
400 m	1,680 ft/s	1,833 ft/s
500 m	1,373 ft/s	1,569 ft/s
600 m	1,106 ft/s	1,323 ft/s

Referenced at: [3]

One expert in wound ballistics, Col. Martin Fackler, M.D., has studied small arms wounding extensively. While some of his findings are controversial among firearms experts, he has performed significant testing of ammunition, including tests into inert test media and into anesthetized pigs as live targets.

The damage done (and apparent incapacitation capability of) 5.56 mm rifle ammunition is significantly enhanced if the bullets fragment on impact. Both M193 55-grain bullets and SS109 62-grain bullets fragment moderately at velocities over 2,500 feet per second, and extensively at velocities over 2,700 feet per second. Even 10-inch barrels for Colt Commando rifles have in excess of 2,700 feet per second muzzle velocity, but rounds will drop below 2,700 ft/s within about 20 meters and below 2,500 ft/s within about 60 meters.

These studies were part of the body of research that led to the M4 Carbine being produced with a 14.5-inch barrel length, which only loses about 50 meters worth of fragmenting range (about 125 meters) compared to the standard 20-inch rifle barrel (about 175 meters) when firing SS109 ammunition.

See for example [4].