HK ~ MR-556 A4 ~ 5.56x45

For Sale: Heckler & Koch MR556 A4 5.56x45mm NATO As New In Box (ANIB) The Absolute Top-Tier, "No Compromise" Heavyweight of the AR World. The Heckler & Koch MR556 A4 is a semi-automatic rifle based on the civilian-legal version of the HK416 platform. It utilizes a short-stroke gas piston operating system, which is designed to keep the action cleaner and cooler compared to standard direct-impingement systems by preventing gas and carbon fouling from entering the receiver. The A4 variant introduces several updates, including an adjustable gas block for suppressed or unsuppressed operation, fully ambidextrous controls, and a lighter profile handguard utilizing the M-LOK system. The rifle features a heavy-contour barrel made from cold hammer-forged steel with a 1:7 twist rate, optimized for durability and accuracy.