HK MR556A1 5.56 NATO 16.5 in AR-15 Piston Rifle, KeyMod Handguard Variant, Factory New (2021) with Troy Folding Sights and HK Soft Case
This Heckler & Koch MR556A1 is a factory-new, unfired commercial counterpart to the HK416 family, built in the USA and manufactured in 2021. It features a 16.5 in cold hammer-forged heavy barrel with a 1:7 twist, a short-stroke gas piston system, and the KeyMod handguard variant with a continuous numbered Picatinny top rail. It comes complete with a steel 30-round magazine, detached Troy folding sights, the original HK soft case and factory case, and the HK MR556A1 Operator's Manual.
Condition
Overall Condition: Factory new condition, unfired with no signs of handling. Includes all accessories and paperwork in the original factory box/case.
Bore Condition: New - As-new bore with no signs of use beyond factory testing.
Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: This MR556A1 appears exactly as it left the HK facility in Columbus, Georgia. The proprietary matte black finish is pristine and uniform across the forged upper and lower receivers with no handling marks, assembly wear, or "safe kisses." The 16.5-inch barrel presents a mirror-bright, factory-new bore with sharp, unfired rifling.
What's Included
- HK soft case
- Original factory case
- HK MR556A1 Operator's Manual
- Troy Industries folding iron sights (front and rear), detached
- Cable lock
- Short bolt-on Picatinny rail sections installed on handguard
- 1x 30-round steel magazine marked "Made in Germany" and "5.56x45"
The MR556A1 employs HK's semi-automatic, short-stroke gas piston system and an AR-15 pattern layout. Its 16.5 in cold hammer-forged heavy barrel is not chrome-lined and uses a 1:7 twist to stabilize a broad range of 5.56 NATO projectiles. A threaded muzzle with a multi-prong flash suppressor is factory-fitted.
This is the KeyMod Handguard variant with a free-float aluminum handguard and a continuous, numbered Picatinny top rail running from the receiver through the handguard. The handguard includes an integral QD sling socket, and short bolt-on Picatinny rail sections are installed for accessory mounting.
The forged aluminum receivers wear HK's proprietary matte black, hard-anodized finish. Controls include a manual safety with HK pictogram markings (Safe/Semi). The bolt carrier is marked "HK MR." The top rail and included detached Troy folding sights give the buyer flexible sighting options without altering the rifle's factory-new status.
Furniture consists of the HK E1 6-position collapsible stock on a MIL-SPEC diameter receiver extension, providing approximately 11–14 in length-of-pull adjustment. The stock has a ribbed buttpad and integral sling loop, and the rifle uses an HK pattern pistol grip with molded texturing. Markings include "Heckler & Koch Inc. Columbus GA," confirming U.S. manufacture in 2021.
Capacity is 30+1 with the included steel magazine.