The M6 is a series of carbines designed and manufactured by LWRC International. It is based on the M4 carbine, with which it shares 80% of its parts.[1] The 'M' model name is not a US military designation. Like the HK416, it features a proprietary short-stroke self-regulating gas piston system and bolt carrier/carrier key design, which prevents trapped gases from contacting the bolt carrier or receiver of the weapon, which reduces the heating and carbon fouling of the internals, simplifies field maintenance, and improves reliability.[1]

LWRC M6A2 in a short barrel configuration with a cerakote "flat dark earth" finish, suppressor and holographic sight.
TypeAssault rifle/Carbine
Place of origin United States
Production history
DesignerLand Warfare Resources Corporation
ManufacturerLWRC International
Unit costUS$2,350
VariantsM6, M6A1, M6A2, M6A3, M6A4
Cartridge5.56×45mm NATO
6.8mm Remington SPC
ActionRotating bolt, selective fire
Rate of fire700–900 rounds/min
Muzzle velocity2,800 ft/s (850 m/s) (5.56 mm from a 14.7 in barrel)
2,500 ft/s (760 m/s) (6.8 mm SPC from a 14.7 in barrel)
Feed systemSTANAG-compliant magazine
Barrett magazine (6.8 mm models)
SightsBUIS Flip-Up iron sights

Standard length barrel is 16.1 in, with a 1:7″ twist (six lands, right twist) barrel with a ferritic nitrocarburized surface conversion which covers the barrel, inside and out, as well as the piston components. Barrel lengths of 10.5″, 12.7″, 14.7″ and 18″ (available for select models) are available.[2]

The Discovery Channel show Future Weapons featured the M6A2 and the M6A4. Additionally, the weapon was featured on the Spike TV show Deadliest Warrior, in the episode "SWAT versus GSG-9", as the main carbine for the SWAT team.



The M6 is LWRC's most basic model. It is the most similar to the M4, but it still has the short-stroke gas piston system common to all LWRC's models.[3]

The M6 has now been replaced by the M6-SL (stretch lightweight) as LWRC's most basic offering.


The M6A1 is also similar to the M4, but is designed to accept SOPMOD accessories similar to the M4A1 used by USSOCOM. The difference between the M6 and the A1 model is the addition of a rail system[4]


The M6A2 is identified by LWRC as its "standard carbine" and has features that allow it to be used in multiple roles beyond a rifle, such as an optional longer barrel allowing it to be used as a designated marksman rifle.[5] It was an approved personal purchase duty carbine of the United States Drug Enforcement Administration[6] in a special configuration called the M6A2 D-DEA, however, it is not standard issue. All A2 series use flip-up iron sights mounted to Mil Std 1913 style rail interfaces as the A2 series lacks a built-in sighting system like those found on A1 and A3 models.[7]

The M6A2 UCIW (Ultra Compact Individual Weapon) was adopted around 2012 in limited numbers by the UK Special Forces. The 7-inch (178 mm) barrel and the overall length of the carbine at 22-inches (559 mm) met the key requirement in the UKSF trials that produced the weapon, which competed successfully for the British contract against the HK416C. The 5.56×45mm NATO UCIW weighs 6.25 lb (2.83 kg) and is apparently intended for use by UKSF dog handlers, team leaders, signallers and for use in vehicles and whilst conducting covert reconnaissance and close protection, replacing the 9×19mm Parabellum MP5K machine pistol in the latter role. The weapon is often seen in Afghanistan with a SureFire suppressor and either an Aimpoint Micro or EO Tech optics.[8][9]

Personal Security Detail

The PSD is an ultra-short barrel carbine with an 8-inch barrel and Magpul CTR stock. Derived from the M6A2 carbine, it comes chambered in 5.56mm NATO or 6.8mm Remington SPC.[10] It is also available without a stock as the M6A2-P Pistol, but is semi-automatic and also chambered in 5.56mm and 6.8mm Remington SPC.[11]


The M6A3 is designed specifically to be a designated marksman rifle. This rifle uses a midlength short stroke gas piston system to reduce recoil and increases the speed of follow up shots.[12] It features an adjustable gas system to allow the user to adapt the rifle to different conditions and is designed to accommodate optics such as scopes and reflex sights. The A3 integrates a gas block using a flip up front sight as opposed to the fixed AR series sight of the M6 and M6A1.[13]


The M6A4 was designed to fulfill the role of the squad automatic weapon. It was developed for the United States Marine Corps' Infantry Automatic Rifle program, which sought to replace some M249s with a more maneuverable weapon.[14] However, it was not accepted for final testing in favor of a Heckler & Koch HK416 variant.[15]

Externally identical to the M6A3, it fires from a closed bolt during semi-automatic fire, and from an open bolt during automatic fire which is labeled as "OBA" for Open Bolt Automatic. While in OBA mode, the first round may be fired from a closed bolt (it will then lock back and subsequent shots will be from an open bolt until the operator manually closes the bolt again). Firing from an open bolt increases cooling and eliminates the potential for accidental discharges due to rounds "cooking off" in an overheated chamber. It also allows for a faster rate of fire. However, an open bolt design meant that the first round fired will have reduced accuracy when compared to a closed bolt design. This is due to the fact that when the trigger is pulled, the bolt slams forward under spring tension, stripping a round from the feeding device, chambering it, then firing it. This sequence of events shakes the firearm and takes longer than a closed bolt design to fire the first round (greater lock time). This also introduces extra potential points of failure in the ignition of the first round.

M6 Individual Carbine

Developed for the eventually cancelled US Army Individual Carbine Competition, the Individual Carbine is a 5.56×45mm weapons system. First batch units used a spiral-fluted barrel in either 14.7 inches or 16.1 inches. Later units returned to a more conventional style. The front gas block differed from other M6-series via a bayonet mounting gas block with flip-up iron sight. The IC-SPR, a sub-variant of the IC, sported a low-profile gas block. The system used a monolithic rail system that was forged as part of the upper receiver. IC comes standard with a Magpul MOE pistol grip, and either a Magpul stock or a proprietary compact stock. The M6-IC was not down selected as part of the competition.[16][17]


The Six8 is a derivative of the M6-series with variants conforming to the M6A2, M6A2 SPR and PSD but engineered specifically around the 6.8×43mm SPCII round. LWRCI partnered with ATK and Magpul to develop the Six8 to fulfill a large overseas military contract. ATK developed the contract ammunition, a 90-grain Gold Dot round optimized for short-barreled rifles. Magpul created a larger variation of their PMAG magazine, called the "Black Widow," with a blood-red follower for the 6.8mm round. The upper and lower receivers were developed specifically to fit this Magpul magazine and optimized around the 6.8×43mm round. The flagship model of the Six8 series is the UCIW which features an 8.5-inch barrel. The A2 and SPR variations feature longer barrel lengths including 12.7, 14.7, and 16.1 inches. Weapons of this series come standard with Magpul MOE pistol grips, LWRCI proprietary compact stocks, and iron sights.[18]


 JordanRoyal Guard6.8 PSD[19]
 Saudi ArabiaRoyal Guard RegimentSix8 UCIW[20]
 SwedenSOG and police tactical unitsM6IC[21]
 SingaporeSOF and various other SOG unitsM6IC
 United Kingdom22nd SAS RegimentM6A2 UCIW[22]
 United States Drug Enforcement Administration (DEA) M6A2


  1. "LWRC Technology". Retrieved 11 November 2014.
  2. "Product Not Found". Archived from the original on 8 September 2012. Retrieved 11 November 2014.
  3. "M6". Archived from the original on 26 December 2009. Retrieved 11 November 2014.
  4. "M6A1". Archived from the original on 8 September 2012. Retrieved 11 November 2014.
  5. "M6A2". Archived from the original on 11 February 2015. Retrieved 11 November 2014.
  6. "DEA". Retrieved 11 November 2014.
  7. "M6A2 D-DEA". Archived from the original on 28 January 2013. Retrieved 11 November 2014.
  8. Neville, Leigh, Guns of Special Forces 2001 - 2015, Pen & Sword Military, 2016, ISBN 1473821061, ISBN 978-1473821064, p.133
  9. "SAS - Weapons - Ultra Compact Individual Weapon | UCIW". www.eliteukforces.info.
  10. "Product Not Found". Archived from the original on 30 November 2009. Retrieved 11 November 2014.
  11. "M6A2-P Pistol". Archived from the original on 19 December 2009. Retrieved 11 November 2014.
  12. "Product Not Found". Archived from the original on 4 September 2012. Retrieved 11 November 2014.
  13. "M6A3". Archived from the original on 4 September 2012. Retrieved 11 November 2014.
  14. X-15.indd
  15. Lamothe, Dan (December 14, 2009). "Frontrunner chosen in IAR contest". Marine Corps Times. p. 20.
  16. https://www.lwrci.com/articles/GA-NOV-P48-55.pdf%5B%5D
  17. https://www.lwrci.com/articles/STMP-120300-LWR.pdf%5B%5D
  18. "Magpul's Magazine for the LWRC Six8 UICW Carbine - Soldier Systems Daily". Retrieved 11 November 2014.
  19. "LWRC rifles to be license-produced in Jordan -". May 13, 2010.
  20. Harrison, Iain (August 27, 2019). "LWRC Six8-PDW". Recoil.
  21. "BREAKING: Swedish SOG and Special Police units to get LWRCI Rifles -". November 29, 2016.
  22. Neville, Leigh, and Dennis, Peter, The SAS 1983-2014 (Elite), 2016, Osprey Publishing, ISBN 1472814037 ISBN 978-1472814036
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