*UPDATE: Check out another test of the Heckler & Koch MR556A1-SD rifle by Jason Swa here!

Heckler & Koch’s (HK) MR556A1 and MR762A1 are two of the most sought after AR-type rifles today. These civilian versions of the HK416 and HK417 provide the same reliability, proven combat effectiveness and quality for the average gun buyer. Using one of the most popular gas-piston systems today, they are proven across a broad range of barrel sizes, calibers and configurations. They remain one of the favorite platforms for elite military and police units all over the world. Continuing on this trend are the SD (suppressed) models for the MR556A1 and MR762A1.

Available as a package only through Operators Suppressor Systems (OSS), the MR556A1-SD and MR762A1-SD rifles feature OSS’ revolutionary suppressor design. Each rifle is equipped with a new forend designed specifically to work with these suppressors. This includes a flash suppressor/muzzle brake that attaches over the barrel and under the forend. OSS’ Back Pressure Regulator fits over it, adding less than an inch to the overall length of the rifle. Suppression is excellent, and when you add the Signature Reduction Module, it gets even quieter. Back-pressure is minimal with this system, meaning little or no effect on operation.

Take a look at some video of my testing process with both of these rifles. The MR762A1-SD is designed specifically as a precision rifle, while the MR556A1-SD fits any combat carbine role. Stay tuned for complete reviews of both rifles in upcoming issues of TACTICAL WEAPONS and SPECIAL WEAPONS FOR MILITARY & POLICE and see if the buzz on these rifles is matched by their performance. For more information, visit



ON LOCATION IN UTAH: When shooting the cover photography for the May 2014 issue of TACTICAL WEAPONS magazine, Jason Swarr of Straight 8 Photography recorded a video of testing the Heckler & Koch MR556A1-SD rifle at the Operators Suppressor Systems (OSS) headquarters in Murray, Utah. The rifle utilizes OSS’ two-piece sound-suppression design consisting of a Back Pressure Regulator (BPR) and a Signature Reduction Module (SRM). For ammo, they used 55-grain 5.56mm FMJs.


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