Heckler & Koch MR556A1 5.56mm NATO Semi-Auto Rifle with 16.5" CHF Barrel & M-LOK Handguard
The HK MR556A1 delivers the renowned HK416 short-stroke piston system in a civilian-legal, semi-automatic platform. Built around a German cold-hammer-forged barrel and assembled on hard-coat anodized 7075-T6 receivers, this rifle offers exceptional durability, clean operation, and a smooth recoil impulse. Collectors and serious shooters appreciate its German CIP proofs, premium build quality, and ready-to-customize M-LOK handguard.
Condition
Overall Condition: Excellent condition, showing only faint signs of any prior use or handling.
Bore Condition: Excellent – Clean, mirror finish, no signs of wear.
Rifling: Excellent – Sharp lands and grooves.
Specific Condition Notes: Minor handling marks are present on high-contact surfaces, but the finish remains uniform. The bore is bright and free of fouling.
What’s Included
- Original HK case
- HK MR556A1 operator’s manual
- 1 Magpul PMAG 30-round polymer magazine
The MR556A1’s closed short-stroke piston system runs cooler and cleaner than direct-impingement designs, reducing maintenance demands and extending parts life. This system is directly derived from the combat-proven HK416.
Its 16.5" cold-hammer-forged, nitrocarburized medium-contour barrel is rated for 20,000+ rounds and finished with 1:7" RH twist for optimal projectile stability. The threaded muzzle allows easy attachment of flash hiders, brakes, or suppressors.
The free-float aluminum M-LOK handguard provides a rigid platform for accessories without affecting barrel harmonics. Integrated QD sling sockets and top Picatinny rail segments add versatility straight from the box.
Forged 7075-T6 upper and lower receivers feature hard-coat anodized matte black finish, selector pictogram markings, and tight fitment for solid lock-up. German CIP 'HK P CC' proof marks verify pressure testing and quality control.
An adjustable six-position polymer stock with rubber butt-pad caters to shooters of different statures, while flip-up iron sights offer immediate, reliable sighting out of the case.