HK MR556A1 5.56 NATO Semi-Automatic Rifle | AR-15-Pattern, Short-Stroke Piston, 16.5" CHF Barrel, Fixed-Magazine Compliance
The Heckler & Koch MR556A1 is the civilian evolution of the battle-proven HK416 platform, delivering exceptional reliability through a short-stroke gas piston system and cold-hammer-forged barrel. This custom example adds a fixed-magazine compliance device, allowing ownership in restrictive jurisdictions while preserving the rifle’s renowned accuracy and tight tolerances.
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: Minor, superficial scratches and small blemishes are present but do not affect function or appearance under normal inspection.
What’s Included
- HK-branded padded rifle bag (black, MOLLE-equipped)
- One 10-round steel factory magazine
Built on a 7075-T6 forged-aluminum receiver set, the MR556A1 combines HK’s piston-driven operating system with an unlined, taper-bore 16.5" cold-hammer-forged barrel for consistent accuracy and extended life. The barrel is threaded 1/2-28 UNEF, ready for muzzle devices or suppressor mounts.
A compliance-oriented fixed-magazine conversion replaces the standard magazine release; reloading requires separating the upper from the lower, keeping the rifle legal where detachable magazines are restricted. Despite this modification, ambidextrous controls—including the safety selector—remain fully functional.
The rifle-length free-float aluminum handguard, adopted by HK in 2023, offers M-LOK slots at the 3, 6, and 9 o’clock positions plus a full Picatinny top rail. This optics-ready flat-top configuration ships without iron sights, giving the owner full freedom to mount optics and accessories.
An adjustable six-position polymer stock pairs with a Magpul grip for user-tunable ergonomics, while precise manufacturing yields notably tight tolerances characteristic of HK’s premium line. Proof markings and Columbus, GA import stamp verify authentic U.S. importation.