Heckler & Koch has brought production versions of a civilian AR-style gas piston rifle based on the HK416 platform to SHOT Show 2011 this week in Las Vegas.

The new rifle, called the MR556A1, is "inspired and influenced by the HK416, the selective fire rifle that widely viewed as a leading candidate to replace the U.S. military's current M4 carbine," according to the company. The rifle has also been adopted by law enforcement agencies.

The 5.56x45mm MR556A1 would be available for purchase by off-duty law officers — the HK416 is an agency issued rifle only — and employs a gas piston operating system with a piston and "pusher" rod in place of a gas tube.

This method of operation virtually eliminates malfunctions more common to direct impingement gas systems. With this rifle, hot carbon fouling and waste gases don't enter the receiver.

The MR556A1 carries over many of the same assemblies and accessories originally developed for the HK416, including the free-floating four-quadrant rail system. This handguard system allows the MR556A1 to accept sights, lights, and other M4-type accessories.

The rifle's rail system can be installed and removed without tools and returns to zero when reinstalled. The MR556A1's barrel is cold-hammer forged.

As a departure from the HK416, the 16.5-inch MR556A1 barrel is not chrome lined. By using high-quality steel, an longer service life barrel can be produced without chroming. According to H&K engineers, chrome lining may add to barrel life but it does not contribute significantly to accuracy and can temporarily conceal defects in the barrel profile.

Related:

H&K Is Developing Two More Patrol Carbines