The M6 carbine is an AR-15-based weapon. It was designed by LWRC International.
LWRC International made a couple of changes to the AR system: based the M6 on an AR short-stroke gas piston operating system and chambered the rifle in a more ballistically effective round; the Remington 6.8 SPC,which produces 45% more kinetic energy than the current issued 5.56 NATO round. The M6 and variants are also available in 5.56 NATO.
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. The M6 lacks a rail system and instead uses a variation of the hemispherical polymer handguards found on almost all stock M4 clones.
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.
The M6A2 is identified by LWRC as its "standard carbine" and has features that allow it to be used in multiple roles in addition to an assault weapon, such as an optional longer barrel allowing it to be used as a designated marksman rifle.It is a duty weapon of the United States Drug Enforcement Administration in a special configuration called the M6A2 D-DEA. All A2 series use back up iron sights mounted to their Mil Std 1913 style rail interface as the A2 series lacks a built in sighting systems like those found on the A1 and A3 models.
Personal Security DetachmentEdit
The PSD is an ultra short barrel carbine with an 8-inch (200 mm) barrel and Magpul CTR stock. Derived from the M6A2 Carbine it comes chambered in 5.56mm or 6.8 SPC. It is also available without a stock as the M6A2-P Pistol but is semi-automatic and also chambered in 5.56mm and 6.8 Remington SPC.
The M6A3 is designed specifically to be a designated marksman rifle. 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.
The M6A4 is 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. However, it was not accepted for final testing in favor of a Heckler & Koch HK416 variant.
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 means 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.