Heckler & Koch HK MR556A1 5.56mm NATO Semi-Auto Rifle, 16.5 in CHF Heavy Barrel, Short-Stroke Gas Piston, Free-Float M-LOK
The HK MR556A1 stands out for its 16.5 inch heavy, cold-hammer-forged steel barrel with an unlined taper-bore and 1:7 RH twist, paired with Heckler & Koch's short-stroke gas piston system. It features a free-float, rifle-length M-LOK aluminum handguard with integral QD sockets and a full-length, T-marked Picatinny top rail. Assembled in the USA using a mix of U.S. and German components, this example carries HK shield CD (2023) markings and presents in excellent condition.
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.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: This firearm presents in great shape, with minor scratches and small blemishes visible upon close inspection.
What's Included
- Original case
- Straps for carry case
- Toolset
- Manual
- 1x 30-round Magpul PMAG Gen M3 polymer magazine for 5.56x45
The 16.5 inch barrel is heavy contour, cold-hammer-forged, unlined, and taper-bored with six grooves and a 1:7 RH twist. It is threaded at the muzzle and fitted with a factory birdcage flash hider. The chamber is CIP-dimensioned for 5.56x45 mm NATO and is compatible with quality .223 Rem ammunition.
HK's short-stroke gas piston action delivers piston-driven operation. The bolt carrier is marked HK MR, and the upper and handguard bear the HK shield with CD date code. A dust cover, case deflector, and forward assist are present.
The rifle-length, free-float M-LOK aluminum handguard includes integral QD sling sockets and mates to a full-length, T-marked Picatinny top rail. No sights are installed from the factory.
Furniture and controls include the HK E1 collapsible stock with rubber buttpad and integral sling loop, a Magpul pistol grip, an ambidextrous manual safety selector, and a two-stage trigger. Overall length is approximately 33.90 to 37.68 inches, and weight is about 8.60 lb without a magazine. Capacity is 30+1. The receiver is aluminum, and the rifle is assembled in the United States using U.S. and German-made components.