cqbr

The Close Quarters Battle Receiver is a replacement upper receiver for the M4A1 carbine. Its preliminary National Stock Number is 1005-LL-L99-5996. The overall length of the upper receiver is 19.25 inches. With the stock retracted, the overall length of the weapon is 26.25 inches. 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 suited to the task. One of two proposed special mission recievers that were planned for inclusion into the SOPMOD Block IV kit, the CQBR has taken off on its own. Like the proposed Special Purpose Reciever, the Close Quarters Battle Reciever 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 end of the SOPMOD program. While the Special Purpose Reciever morphed into the Special Purpose Rifle, and was type classified as Mk 12 Mod 0/1, the CQBR has not yet been type classified. The purpose of the CQBR remains to provide operators with a weapon of submachinegun size, but firing a rifle catridge, for scenarios such as VIP protection, urban warfare, and other Close Quarters Battle situations. The CQBR is designed to provide improvement over previous AR15/M16 type weapons in this category. The CQBR is usually issued as a whole weapon, and not just an upper receiver. The short 10.3" barrel length requires special modifications to reliably function. The gas port is opened to 0.70" from 0.62". A one-piece McFarland gas ring replaces the three-piece gas ring set. The standard 4-coil extractor spring is replaced with a commercial off-the-shelf (COTS) 5-coil spring. An o-ring surrounds the extractor spring.

Specifications

Upper and Lower Receiver: The lower receiver is a standard M4A1 lower receiver with no modifications. 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 0.70". The charging handle is a PRI M84 Gas Buster charing with with a Big Latch.

Sights: Initially, detachable carrying handles cut down so that only the rear sight assembly, were used. However, most of these have been replaced with the similar commercially-made Lewis Machine & Tools rear sight.

Stock: A variety of M4 retractable buttstocks are used on a standard 4-position receiver extension. 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 off 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 SOPMOD stocks are made by Lewis Machine & Tools and have none of the problems.

Barrel: The CQBR uses a standard 1:7" twist M4 barrel that has been reduced in length to 10.3". The diameter of the barrel under the handguards is 0.625". The KAC QD flash suppressor is fitted, allowing use of the KAC QD Suppressor (National Stock Number 1005-01-437-0324). Though it has a bayonet lug, the CQBR is not meant to be fitted with a bayonet.

Handguards: The standard handguard for the CQBR is the Knight's Armament Company Rail Interface System (National Stock Number 1005-01-416-1089), which allows for the usage of any accessories that are compatible with MIL-STD-1913 rails.

Photos

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Cqbr

Background

Specifications

Photos

See also