CQBR
Encyclopedia
The Close Quarters Battle Receiver (CQBR) is a replacement upper receiver for the M4A1 Carbine
. The CQBR replaces the M4 with a barrel 10.3 in (262 mm) length making it the modern equivalent of the Colt Commando
short-barrel M16 variants of the past.
Its preliminary National Stock Number was 1005-LL-L99-5996; however, a complete CQBR-equipped carbine now has the NSN 1005-01-527-2288. The overall length of the upper receiver is 19.25 inches (489 mm). With the stock
retracted, the overall length of the weapon is 26.25 inches (667 mm). The CQBR entered service in 2000.
Block II kit, the CQBR has taken off on its own. Like the proposed Special Purpose Receiver, the Close Quarters Battle Receiver has been more or less taken on by the Naval Surface Warfare Center, Crane Division
(often referred to as NSWC-Crane or just "Crane") as its own project following the CQBR's removal from the SOPMOD program. Just as the Special Purpose Receiver morphed into the Special Purpose Rifle, and was type-classified as Mk 12 Mod 0/1
, the complete CQBR-equipped carbine has been type-classified as the Mk 18 Mod 0.
The purpose of the CQBR remains to provide operators with a weapon of submachine gun
size, but firing a rifle
cartridge
, for scenarios such as VIP protection
, urban warfare
, and other close quarters battle
(CQB) situations. The CQBR is designed to provide improvement over previous AR-15
/M16
-type weapons in this category. The CQBR is usually issued as a complete weapon system, and not just an upper receiver. The CQBR was once only available to Naval Special Warfare units, but the Mk 18 Mod 0 has become general issue for Visit, Board, Search, and Seizure (VBSS) missions and, as of 2006, for NCIS
agents deploying to active combat zones. The Mk 18 is also used by the Coast Guard's
Tactical Law Enforcement Teams
, Maritime Safety and Security Team
s, and Maritime Security Response Team and the United States Navy's Explosive Ordnance Disposal (EOD) Operators
. It is also used by Marine Force Recon's CQB operators, and is in most cases the standard weapons of choice for said operators.
The short 10.3 in (262 mm) barrel length requires special modifications to reliably function. The gas port is opened from 0.062 to 0.070 in (0.16 to 0.18 mm). A one-piece McFarland gas ring replaces the three-piece gas ring set. The standard four-coil extractor spring is replaced with a commercial off-the-shelf (COTS) five-coil spring. An O-ring surrounds the extractor spring. The standard M4 flash hider has been replaced with the M4QD flash hider for suppressor compatibility.
M4 carbine
The M4 carbine is a family of firearms tracing its lineage back to earlier carbine versions of the M16, all based on the original AR-15 designed by Eugene Stoner and made by ArmaLite. It is a shorter and lighter variant of the M16A2 assault rifle, with 80% parts commonality.It is a gas-operated,...
. The CQBR replaces the M4 with a barrel 10.3 in (262 mm) length making it the modern equivalent of the Colt Commando
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 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...
short-barrel M16 variants of the past.
Its preliminary National Stock Number was 1005-LL-L99-5996; however, a complete CQBR-equipped carbine now has the NSN 1005-01-527-2288. The overall length of the upper receiver is 19.25 inches (489 mm). With the stock
Stock (firearm)
A stock, also known as a buttstock or shoulder stock, is a part of a rifle or other firearm, to which the barrel and firing mechanism are attached, that is held against one's shoulder when firing the gun. Stocks are also found on crossbows though a crossbow stock is more properly referred to as a...
retracted, the overall length of the weapon is 26.25 inches (667 mm). The CQBR entered service in 2000.
Background
The M4 and M16 are not ideally suited for all missions, so it was proposed that the modularity of the M16 series would allow a user to replace the upper receiver of an existing weapon with one more suitable to the task. One of two proposed special mission receivers that were planned for inclusion into the SOPMODSOPMOD
The Special Operations Peculiar MODification kit is an accessory system for the M4A1 carbine and FN SCAR Mk 16/17 used by USSOCOM...
Block II kit, the CQBR has taken off on its own. Like the proposed Special Purpose Receiver, the Close Quarters Battle Receiver has been more or less taken on by the Naval Surface Warfare Center, Crane Division
Naval Surface Warfare Center Crane Division
Naval Surface Warfare Center Crane Division is the principal tenant command located at Naval Support Activity Crane. NSA Crane is a United States Navy installation located approximately southwest of Bloomington, Indiana and predominantly located in Martin County, but small parts also extend into...
(often referred to as NSWC-Crane or just "Crane") as its own project following the CQBR's removal from the SOPMOD program. Just as the Special Purpose Receiver morphed into the Special Purpose Rifle, and was type-classified as Mk 12 Mod 0/1
United States Navy Mark 12 Mod X Special Purpose Rifle
The United States Navy Mark 12 Mod 0/1 Special Purpose Rifle is a rifle in service with United States Special Operations Forces in Operation Enduring Freedom and Operation Iraqi Freedom...
, the complete CQBR-equipped carbine has been type-classified as the Mk 18 Mod 0.
The purpose of the CQBR remains to provide operators with a weapon of submachine gun
Submachine gun
A submachine gun is an automatic carbine, designed to fire pistol cartridges. It combines the automatic fire of a machine gun with the cartridge of a pistol. The submachine gun was invented during World War I , but the apex of its use was during World War II when millions of the weapon type were...
size, but firing a rifle
Rifle
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...
cartridge
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
, for scenarios such as VIP protection
Executive Protection
Executive Protection also known as Close Personal Protection or bodyguarding refers to security measures taken to ensure the safety of VIPs or other individuals who may be exposed to elevated personal risk because of their employment, celebrity status, wealth, associations or geographical...
, urban warfare
Urban warfare
Urban warfare is combat conducted in urban areas such as towns and cities. Urban combat is very different from combat in the open at both the operational and tactical level...
, and other close quarters battle
Close quarters battle
Close quarters combat or close quarters battle is a type of fighting in which small units engage the enemy with personal weapons at very short range, potentially to the point of hand-to-hand combat or fighting with hand weapons such as swords or knives...
(CQB) situations. The CQBR is designed to provide improvement over previous AR-15
AR-15
The AR-15 is a lightweight, 5.56 mm, air-cooled, gas-operated, magazine-fed semi-automatic rifle, with a rotating-lock bolt, actuated by direct impingement gas operation. It is manufactured with the extensive use of aluminum alloys and synthetic materials....
/M16
M16 rifle
The M16 is the United States military designation for the AR-15 rifle adapted for both semi-automatic and full-automatic fire. Colt purchased the rights to the AR-15 from ArmaLite, and currently uses that designation only for semi-automatic versions of the rifle. The M16 fires the 5.56×45mm NATO...
-type weapons in this category. The CQBR is usually issued as a complete weapon system, and not just an upper receiver. The CQBR was once only available to Naval Special Warfare units, but the Mk 18 Mod 0 has become general issue for Visit, Board, Search, and Seizure (VBSS) missions and, as of 2006, for NCIS
Naval Criminal Investigative Service
The United States Naval Criminal Investigative Service is the primary security, counter-intelligence, counter-terrorism, and law enforcement agency of the United States Department of the Navy...
agents deploying to active combat zones. The Mk 18 is also used by the Coast Guard's
United States Coast Guard
The United States Coast Guard is a branch of the United States Armed Forces and one of the seven U.S. uniformed services. The Coast Guard is a maritime, military, multi-mission service unique among the military branches for having a maritime law enforcement mission and a federal regulatory agency...
Tactical Law Enforcement Teams
Law Enforcement Detachments
Law Enforcement Detachments or LEDETs are specialized, deployable maritime law enforcement teams of the United States Coast Guard. First established in 1982, their primary mission is to deploy aboard U.S. and allied naval vessels to conduct and support law enforcement, interdiction, or security...
, Maritime Safety and Security Team
Maritime Safety and Security Team
A Maritime Safety and Security Team or MSST is a United States Coast Guard anti-terrorism team established to protect local maritime assets...
s, and Maritime Security Response Team and the United States Navy's Explosive Ordnance Disposal (EOD) Operators
United States Navy EOD
United States Navy Explosive Ordnance Disposal technicians render safe all types of ordnance, including improvised, chemical, biological, and nuclear. They perform land and underwater location, identification, render-safe, and recovery of foreign and domestic ordnance...
. It is also used by Marine Force Recon's CQB operators, and is in most cases the standard weapons of choice for said operators.
The short 10.3 in (262 mm) barrel length requires special modifications to reliably function. The gas port is opened from 0.062 to 0.070 in (0.16 to 0.18 mm). A one-piece McFarland gas ring replaces the three-piece gas ring set. The standard four-coil extractor spring is replaced with a commercial off-the-shelf (COTS) five-coil spring. An O-ring surrounds the extractor spring. The standard M4 flash hider has been replaced with the M4QD flash hider for suppressor compatibility.
Evolution
- CQBR type 1: Made from M4A1 uppers by shortening the barrels and opening gas ports, no longer produced, STD carbine buffer in use in host lowers at time of fielding.
- CQBR type 2: NSWC assembled with contracted and /or overhauled parts complete with all accessories to current standards at time of build, will work with H, H2 or H3 balanced to ammo requirements:
- H okay with M193/M855.
- H2 needed for MK 262/R2LP & will run M193/M855.
- H3 may be needed for an extreme case, or when the gas port is eroded but the barrel still groups.
- CQBR type 2A: NSWC assembled with contracted and /or overhauled parts, naked without any accessories or buffer. The buffer in the host carbine would be used or upgraded as necessary via the supply system same as type 2.
- CQBR type 3: Colt-contracted upper complete with all accessories. NO buffer supplied. The buffer in the host carbine would be used or upgraded as necessary via the supply system same as type 2.
- CQBR type 3A: Colt-contracted upper naked without any accessories or buffer supplied. The buffer in the host carbine would be used or upgraded as necessary via the supply system same as type 2.
- MK18 type 1: NSWC assembled carbine with contracted and /or overhauled parts complete with all accessories to current standards at time of build will work with H or H2 and could have shipped with either. Units will balance buffer to ammo requirements:
- H okay with M193/M855. (all ship board MK 18’s should have H buffers as this was the standard at the time of assembly).
- H2 needed for MK 262/ R2LP & will run M193/M855.
- H3 may be needed for an extreme cases or when the gas port is eroded but the barrel still groups.
- MK18 type 2: Colt-contracted carbine complete with all accessories H buffer supplied. Units will balance buffer to ammo requirements same as Mk 18 type 1.
Specifications
- Upper and lower receivers: The lower receiver is a standard M4A1 lower receiver sometimes modified with the addition of a CQD RSM sling adapter plate. However, many CQBR rifles also use surplus M16A1 lower receivers. Internally, the CQBR also takes advantage of a larger gas port and modified bolt carrier and buffer assembly. The gas port has been opened to 0.070 in (0.18 mm). A number of Lewis Machine & Tool 10.5" (266.7 mm) upper receivers have also been reported to have been purchased for the CQBR program. These upper receivers feature a gas system optimized for short barrel use.
- Sights: Initially, detachable carrying handles cut down so that only the rear sightIron sightsIron sights are a system of shaped alignment markers used as a sighting device to assist in the aiming of a device such as a firearm, crossbow, or telescope, and exclude the use of optics as in telescopic sights or reflector sights...
assembly was used. However, most of these have been replaced with the similar, commercially-made Lewis Machine & Tool adjustable rear sight. Also used are several types of reflex and magnified optics, most commonly seen is the Aimpoint CompM2Aimpoint CompM2The CompM2 is a battery powered non-magnifying red dot type of reflex sight for firearms manufactured by Aimpoint AB. In the U.S. military, it is designated M68 Close Combat Optic and is also known as M68 Aimpoint and is designed to meet United States military standards...
in a Wilcox Industries Corp. PicatinnyPicatinny railThe Picatinny rail or MIL-STD-1913 rail or STANAG 2324 rail or a "Tactical Rail" is a bracket used on some firearms in order to provide a standardized mounting platform. A similar system is the Weaver rail mount.-Description:...
(MIL-STD-1913) mount.
- Stock: A variety of M4 retractable buttstocks are used on a standard 4-position receiver extension, including the standard "CAR" stock. Most often seen is the SOPMOD stock, often referred to as the "Crane stock", created by Dave Armstrong of NSWC-Crane. The angled stock offers better cheekweld as well as providing two storage compartments for spare batteries. The stock must be removed from the weapon to access the storage compartments. The initial run of stocks was made by NSWC-Crane from glass fiber polymer. Because of this, they were somewhat fragile and did not always properly lock into the receiver extension. A rubber band was used to secure the latch so it would not slide out of the desired position. The current L7LA2B SOPMOD stocks are made by Lewis Machine & Tools and have none of these problems.
- Barrel: The CQBR uses a 1:7 in (178 mm) twist M4 barrel that has been modified in length to 10.3 in (262 mm). The diameter of the barrel under the handguards is 1.17 in (29.7 mm). The KAC M4-QD flash suppressorFlash suppressorA flash suppressor, also known as a flash guard, flash eliminator, flash hider, or flash cone, is a device attached to the muzzle of a rifle or other gun that reduces the visible signature of the burning gases that exit the muzzle. This reduces the chances that the shooter will be blinded in dark...
is fitted, allowing use of the KAC QDSS-NT4 suppressor (National Stock NumberNATO Stock NumberA NATO Stock Number, or National Stock Number as it is known in the US, is a 13-digit numeric code, identifying all the 'standardized material items of supply' as they have been recognized by all NATO countries including United States Department of Defense...
1005-01-437-0324). Although it has a bayonetBayonetA bayonet is a knife, dagger, sword, or spike-shaped weapon designed to fit in, on, over or underneath the muzzle of a rifle, musket or similar weapon, effectively turning the gun into a spear...
lug, the CQBR is not meant to be fitted with any fighting blades.
- Handguards: The standard handguard for the CQBR is the Knight's Armament CompanyKnight's Armament CompanyKnight's Armament Company is an American firearms and firearms parts manufacturer.It is owned by C. Reed Knight and based in Titusville, Florida. KAC is best known for producing the Rail Interface System and the Rail Adapter System grips for military firearms...
Rail Interface System (M4 Carbine RIS; National Stock Number 1005-01-416-1089), which is designed for a variety of barrel profiles and allows for the use of any MIL-STD-1913 tactical accessories such as the AN/PEQ-2AN/PEQ-2The AN/PEQ-2 Target Pointer/Illuminator/Aiming Light is a laser sight for use on rifles fitted with a Picatinny rail. It is manufactured by Insight Technology.The device is mil-spec and is currently in active service with the US armed forces...
infraredInfraredInfrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
pointer, SureFireSurefireSureFire, LLC. is a Fountain Valley, California company whose primary products are flashlights, headlamps, weapon mounted lights and laser sights. In addition, Surefire also manufactures knives, sound suppressors, Picatinny Rails and batteries. The company is a major supplier of flashlights to the...
flashlights, or a vertical forward grip.
- Ammunition: The CQBR is designed to use standard 5.56x45mm NATO5.56x45mm NATO5.56×45mm NATO is a rifle cartridge developed in the United States and originally chambered in the M16 rifle. Under STANAG 4172, it is a standard cartridge for NATO forces as well as many non-NATO countries. It is derived from, but not identical to, the .223 Remington cartridge...
62-grain M855 FMJ and M856 Tracer ammunition. However, due to the short barrel, the heavier 77-grain Mk 262 cartridge is preferred. There are no plans to rechamber the weapon in any additional caliberCaliberIn guns including firearms, caliber or calibre is the approximate internal diameter of the barrel in relation to the diameter of the projectile used in it....
s.