HK MR556 A4 Pistol 11" 5.56 NATO, Short-Stroke Piston, M-LOK Free-Float, Ambidextrous Controls
This Heckler & Koch MR556 A4 Pistol pairs HK's proven short-stroke gas piston system with an 11" cold-hammer-forged, match-grade barrel for a compact, durable 5.56 NATO platform. It features a slim free-float M-LOK handguard with a bolt-on M-LOK QD sling mount and a continuous T-marked top Picatinny rail, fully ambidextrous controls with a safety selector, and an extended ambidextrous charging handle. Markings and configuration are consistent with the MR A4 Series, and this example is in excellent overall 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 - Sharp lands and grooves.
Specific Condition Notes: Shows little sign of prior use. The firearm presents in excellent condition, and the bore is clean and shiny.
What's Included
- HK-branded soft case
- Original case
- HK MR A4 Series operator's manual
- HK-branded red multi-tool
- One 30-round Magpul PMAG GEN M3 magazine
The 11" barrel is steel, cold-hammer-forged, match-grade, and threaded 1/2x28 with 6-groove rifling and a 1:7 RH twist. An open-prong flash hider is installed on the threaded muzzle.
The MR556 A4 Pistol uses HK's semi-automatic, gas-operated short-stroke piston system with a rotating bolt. It is equipped with an HK416-style two-position adjustable gas block (suppressed/unsuppressed), with piston components visible through ports in the handguard.
The slim, free-float aluminum M-LOK handguard includes a bolt-on M-LOK QD sling mount and a continuous T-marked top Picatinny rail. The lower is fully ambidextrous, with ambidextrous magazine release and bolt catch/release, a safety selector with HK pictogram markings, and an extended ambidextrous dual-latch charging handle.
Receiver markings include "MR 556 A4" and "5.56 mm x 45" on the lower, "Heckler & Koch Inc., Columbus, GA" on the magwell, and "HK MR" on the ejection port cover. The pistol is configured with a pistol buffer tube and no stock or brace. It accepts AR-pattern detachable magazines and has a 30+1 capacity.