Featuring a self-regulating, short-stroke piston system of operation, the M6A1-S 5.56x45mm carbine is an LEO-specific tactical tool for the officer on the beat. It is shown equipped with an Aimpoint CompM4s and TangoDown bipod.
ARGUABLY, handguns are not very efficient fight-stoppers—but cops carry them because they are convenient. The gun is always there, yet it’s not too cumbersome when getting in and out of a car or subduing an unruly subject. When it’s time to go to guns though, most gun-savvy officers want a long gun simply because it carries a bigger punch and is more likely than a handgun to quickly incapacitate an offender who needs to be stopped. Recognizing this, more and more agencies are authorizing patrol officers to carry an AR-style carbine. One such suitable weapon is from LWRCI of Cambridge, Maryland.
LWRCI manufacturers several versions of the AR, but all are characterized by a piston-driven operating system instead of the direct gas impingement (DGI) system that has been the subject of much controversy since the AR-15 was first adopted as the M16 by the U.S. military in the mid-twentieth century. The DGI system bleeds propellant gas from a port in the barrel and channels it directly into the receiver and bolt carrier in order to cycle the gun. The gas is not only hot, which reduces component life, but is loaded with carbon and other substances which tend to foul the system and requires lots of lubrication to prevent stoppages. The gas piston system is an attempt to solve this problem by transferring the energy derived from expanding combustion gas through a mechanical linkage to the bolt carrier, so that gas never makes it to the receiver.
The bolt carrier assembly looks like that of a standard AR-15 except that it is finished in a proprietary nickel plating and has an integral thrust shoulder against which the piston rod pushes to drive the assembly to the rear.
Several manufacturers offer piston systems but LWRCI’s version, which was originally introduced in 2004 and has since undergone some improvements, uses a segmented piston rod that the company says is superior to one-piece designs. According to Darren Mellors, LWRCI’s Executive Vice President, it is very difficult to properly machine and heat-treat a long, thin piston rod that will last the service life of an AR without bending. LWRCI’s solution is a three-piece system that allows a little play and reduces the chance of parts bending, which can cause a stoppage.