Top: An M4A1 with SOPMOD package, including Rail Interface System and Trijicon 4× ACOG. The barrel length is 14.5 inches (368 mm). Bottom: An M4A1 with a Close Quarter Battle Receiver. The barrel length is 10.3 inches (262 mm).
The CQBR features a 10.3 in (262 mm) length barrel (similar to the Colt Commando short-barreled M16 variants of the past) which makes the weapon significantly more compact, thus making it easier to use in, and around, vehicles and in tight, confined spaces. The overall length of the upper receiver is 19.25 inches (489 mm). With the stock retracted, the overall length of the weapon is 26.75 inches (679.4 mm). Those created as complete rifles (rather than only upper receivers) are type designated as MK 18 MOD 0/1.
The M4 carbine and M16 are not ideally suited for all missions due to their relatively long barrels, but the modularity of AR pattern rifles allows the operator to easily replace the upper receiver. One of two proposed special mission receivers that were planned for inclusion into the SOPMOD 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, or the Mk 18 MOD 1 with a sightless gas block and full-length accessory rail kit.
The short 10.3 in (262mm) barrel length requires special modifications to function reliably. The gas port is opened from 0.062 to 0.070 in (1.6 to 1.8mm). 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.
Ballistic performance
Shortening the barrel by 50% from the original 20 inches (508 mm) pattern has a dramatic effect on the velocity of 5.56x45mm NATO ammunition. With a 20" barrel, the bullet is moving at 3,071 ft/s (936 m/s), but this drops to 2,489 ft/s (759 m/s) at 10".[4] This has led some to question the effectiveness[5] of the Mk 18 compared to other cartridges like 7.62×39mm or .300 AAC Blackout which are not as affected by barrel length reduction.
Model
Barrel length in inches
Muzzle velocity (feet per second)
Change in velocity compared to 26" barrel (feet per second)
26
3182
M16
20
3071
-111
16.5
2968
-214
Mk 18
10
2489
-693
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:
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.[citation needed]
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 and M855. (All shipboard MK 18s should have H buffers as this was the standard at the time of assembly.)
H2 needed for MK 262, MK255 R2LP, or MK 311 R2LP; will still reliably 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.
MK18 MOD 0 (MK18 MOD O): Designation given to the full rifle, consisting of CQBR upper receiver and M16A1 lower receiver
MK18 MOD 1: Similar to the changes found in the SOPMOD Block II kit, the MOD 1 features a gas block end without a front sight and a railed handguard, by Daniel Defense, that extends all the way to the base of the flash hider to provide more accessory rail space for the user.
Specifications
Navy SEALs conduct Shoot House Training at Little Creek, Virginia in mid 2007. Each Mk18 MOD 0 CQBR carbines has the M68 Aimpoint optic, Knight's Armament QD suppressor and AN/PEQ-2.
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 (1.8 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. The MOD 1 makes use of a forward sight delete and full-length handguard to provide more rail space for the user.
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 & Tool adjustable rear sight. Also used are several types of reflex and magnified optics. Most commonly seen is the Aimpoint CompM2 in a Wilcox Industries Corp. Picatinny (MIL-STD-1913) mount. On the MOD 1, the front sight is deleted and a full-length accessory rail is used; flip up iron sights may be mounted per user preferences.[citation needed]
Stock: A variety of M4 retractable buttstocks are used on a standard 4-position receiver extension, including the standard "CAR" stock. The SOPMOD stock, often referred to as the "Crane stock", created by Dave Armstrong of NSWC-Crane is commonly used. The angled stock offers better cheekweld and provides 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 suppressor is fitted, allowing use of the KAC QDSS-NT4 suppressor (National Stock Number 1005-01-437-0324). Although 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 (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-2, SureFire flashlights, or a vertical forward grip. The standard handguard has since changed to Daniel Defense's MK18 RIS, NSN # 1005-01-548-1385.
Ammunition: The CQBR is designed to use standard 5.56×45mm NATO 62-grain SS109/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 calibers.
^(PDF). Defense Acquisition University. US Navy. 22 August 2008. pp. 85–86. Archived from the original (PDF) on 22 June 2022. Retrieved 22 June 2022.
^. Daniel Defense. Archived from the original on 14 April 2021.
^Johnson, Jeff (14 May 2003). . NDIA. 2003 Joint Services Small Arms Section Annual Symposium, Exhibition, Firing Demonstration & Plant tour: NSWC. Archived from the original on 22 June 2022. Retrieved 22 June 2022.{{cite web}}: CS1 maint: location (link)
^Marr, Bill (7 December 2015). . rifleshooter.com. Archived from the original on 21 October 2021. Retrieved 29 June 2021.
^Garand Thumb, "Is the MK18 obsolete?", Youtube, archived from the original on 12 December 2021, retrieved 29 June 2021
close, quarters, battle, receiver, this, article, technical, most, readers, understand, please, help, improve, make, understandable, experts, without, removing, technical, details, october, 2012, learn, when, remove, this, template, message, this, article, nee. This article may be too technical for most readers to understand Please help improve it to make it understandable to non experts without removing the technical details October 2012 Learn how and when to remove this template message This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Close Quarters Battle Receiver news newspapers books scholar JSTOR June 2022 Learn how and when to remove this template message The Close Quarter Battle Receiver CQBR is a replacement upper receiver for the M4A1 Carbine developed by the US Navy Close Quarter Battle Receiver 1 Top An M4A1 with SOPMOD package including Rail Interface System and Trijicon 4 ACOG The barrel length is 14 5 inches 368 mm Bottom An M4A1 with a Close Quarter Battle Receiver The barrel length is 10 3 inches 262 mm TypeAssault Rifle CarbinePlace of originUnited StatesService historyIn service2000 presentUsed bySee M4 Carbine usersWarsWar in AfghanistanIraq WarProduction historyDesignerColt Defense Daniel Defense 2 Designed1999 citation needed Produced2000 present citation needed No builtApprox gt 10 000Specifications CQBR Mass2 72 kg 6 00 lb Length762 mm 30 0 in stock extended679 4 mm 26 75 in stock retractedBarrel length262 mm 10 3 in Cartridge5 56 45mm NATOActionGas operated rotating boltRate of fire700 950 round min cyclicMuzzle velocity2 585 ft s 788 m s 3 Effective firing range300 m 328 yd Feed system20 or 30 round detachable STANAG magazineSightsIron sights and various SOPMOD sightsThe CQBR features a 10 3 in 262 mm length barrel similar to the Colt Commando short barreled M16 variants of the past which makes the weapon significantly more compact thus making it easier to use in and around vehicles and in tight confined spaces 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 75 inches 679 4 mm Those created as complete rifles rather than only upper receivers are type designated as MK 18 MOD 0 1 Special forces units utilize the CQBR for scenarios such as VIP protection urban warfare and other close quarters battle CQB situations Its former preliminary National Stock Number NSN had been 1005 LL L99 5996 A complete CQBR equipped carbine now has the NSN 1005 01 527 2288 Contents 1 Background 2 Ballistic performance 3 Evolution 4 Specifications 5 See also 6 References 7 External linksBackground EditThe M4 carbine and M16 are not ideally suited for all missions due to their relatively long barrels but the modularity of AR pattern rifles allows the operator to easily replace the upper receiver One of two proposed special mission receivers that were planned for inclusion into the SOPMOD 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 or the Mk 18 MOD 1 with a sightless gas block and full length accessory rail kit The purpose of the CQBR is to provide operators with a weapon of submachine gun size but firing an intermediate 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 and by extension other US Special Operations Forces 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 citation needed The Mk 18 is also used by the Coast Guard s Tactical Law Enforcement Teams and Maritime Security Response Teams and the United States Navy s Explosive Ordnance Disposal EOD Operators It is also used by both Marine Force Recon Teams and Critical Skills operators from MARSOC and is in most cases the standard weapons of choice for said operators where the range of an M4 is not necessary The short 10 3 in 262mm barrel length requires special modifications to function reliably The gas port is opened from 0 062 to 0 070 in 1 6 to 1 8mm 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 Ballistic performance EditShortening the barrel by 50 from the original 20 inches 508 mm pattern has a dramatic effect on the velocity of 5 56x45mm NATO ammunition With a 20 barrel the bullet is moving at 3 071 ft s 936 m s but this drops to 2 489 ft s 759 m s at 10 4 This has led some to question the effectiveness 5 of the Mk 18 compared to other cartridges like 7 62 39mm or 300 AAC Blackout which are not as affected by barrel length reduction Model Barrel length in inches Muzzle velocity feet per second Change in velocity compared to 26 barrel feet per second 26 3182M16 20 3071 11116 5 2968 214Mk 18 10 2489 693Evolution EditCQBR 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 and M855 H2 needed for MK 262 MK 255 R2LP or MK 311 R2LP will still reliably feed and fire 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 citation needed 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 and M855 All shipboard MK 18s should have H buffers as this was the standard at the time of assembly H2 needed for MK 262 MK255 R2LP or MK 311 R2LP will still reliably 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 MK18 MOD 0 MK18 MOD O Designation given to the full rifle consisting of CQBR upper receiver and M16A1 lower receiver MK18 MOD 1 Similar to the changes found in the SOPMOD Block II kit the MOD 1 features a gas block end without a front sight and a railed handguard by Daniel Defense that extends all the way to the base of the flash hider to provide more accessory rail space for the user Specifications Edit Navy SEALs conduct Shoot House Training at Little Creek Virginia in mid 2007 Each Mk18 MOD 0 CQBR carbines has the M68 Aimpoint optic Knight s Armament QD suppressor and AN PEQ 2 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 1 8 mm A number of Lewis Machine amp 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 The MOD 1 makes use of a forward sight delete and full length handguard to provide more rail space for the user 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 amp Tool adjustable rear sight Also used are several types of reflex and magnified optics Most commonly seen is the Aimpoint CompM2 in a Wilcox Industries Corp Picatinny MIL STD 1913 mount On the MOD 1 the front sight is deleted and a full length accessory rail is used flip up iron sights may be mounted per user preferences citation needed Stock A variety of M4 retractable buttstocks are used on a standard 4 position receiver extension including the standard CAR stock The SOPMOD stock often referred to as the Crane stock created by Dave Armstrong of NSWC Crane is commonly used The angled stock offers better cheekweld and provides 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 amp 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 suppressor is fitted allowing use of the KAC QDSS NT4 suppressor National Stock Number 1005 01 437 0324 Although 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 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 2 SureFire flashlights or a vertical forward grip The standard handguard has since changed to Daniel Defense s MK18 RIS NSN 1005 01 548 1385 Ammunition The CQBR is designed to use standard 5 56 45mm NATO 62 grain SS109 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 calibers See also EditAR 15 List of individual weapons of the U S Armed Forces List of assault rifles United States Army Special ForcesReferences Edit NSWC CRANE SAVES 970K FOR NAVSEA SMALL ARMS OFFICE PDF Defense Acquisition University US Navy 22 August 2008 pp 85 86 Archived from the original PDF on 22 June 2022 Retrieved 22 June 2022 MK18 Daniel Defense Archived from the original on 14 April 2021 Johnson Jeff 14 May 2003 CQB Receiver M4A1 Carbine with 10 Inch Upper Receiver NDIA 2003 Joint Services Small Arms Section Annual Symposium Exhibition Firing Demonstration amp Plant tour NSWC Archived from the original on 22 June 2022 Retrieved 22 June 2022 a href Template Cite web html title Template Cite web cite web a CS1 maint location link Marr Bill 7 December 2015 223 Remington 5 56mm NATO barrel length and velocity 26 inches to 6 inches rifleshooter com Archived from the original on 21 October 2021 Retrieved 29 June 2021 Garand Thumb Is the MK18 obsolete Youtube archived from the original on 12 December 2021 retrieved 29 June 2021External links Edit Wikimedia Commons has media related to CQBR category Retrieved from https en wikipedia org w index php title Close Quarters Battle Receiver amp oldid 1126451147, wikipedia, wiki, book, books, library,
