H&K MR556A1 5.56mm Rifle, M-LOK Handguard w/ 16.5” Barrel

Overview

The H&K MR556A1 is the civilian descendant of the legendary HK416, engineered to deliver exceptional reliability, durability, and match-grade accuracy. Featuring Heckler & Koch’s proven short-stroke gas piston operating system, a German cold hammer-forged barrel, and a free-floating M-LOK handguard, the MR556A1 offers premium performance for discerning shooters. Built using American and German components, this rifle combines military-inspired engineering with precision-focused enhancements for competition, training, and defensive applications.

Key Features

• HK short-stroke gas piston operating system for enhanced reliability and cleaner operation
• German-made 16.5” cold hammer-forged barrel with 1:7 twist
• Free-floating M-LOK handguard for improved accuracy and accessory mounting
• Enhanced two-stage trigger for precision shooting
• Flat-top Picatinny upper receiver for optics and accessories
• Retractable adjustable stock with locking feature
• Extended charging handle latch for easier manipulation with optics installed
• Heavy-profile, non-chrome-lined barrel optimized for maximum accuracy
• Compatible with many standard AR-style upper receiver components
• Manufactured in the USA using American and German components

Specifications

• Manufacturer: Heckler & Koch
• Model: MR556A1
• Manufacturer Part Number: 81000579
• UPC: 642230262553
• Caliber: 5.56 NATO / .223 Remington
• Action: Semi-Automatic
• Operating System: Short-Stroke Gas Piston
• Barrel Length: 16.5”
• Barrel Twist: 1:7”
• Overall Length: 33.90”–37.68”
• Weight: 8.6 lbs
• Receiver Material: Aluminum
• Handguard: Free-Float M-LOK
• Stock: Adjustable Synthetic
• Grip: Black Polymer
• Trigger Pull: Approximately 7.64 lbs
• Sight Radius: 14.6”
MPN: 81000579

UPC: 642230262553

Applications

The MR556A1 is ideal for precision shooting, competitive events, tactical training, home defense, and recreational range use. Its piston-driven operating system and premium barrel make it an outstanding choice for shooters seeking maximum reliability and accuracy from an AR-style platform.

Additional Features

• Based on the battle-proven HK416 design trusted by military and law enforcement professionals
• C.I.P.-spec chamber supports reliable operation with 5.56 NATO and quality .223 Remington ammunition
• Heavy-contour barrel features a slight internal taper to enhance velocity and accuracy
• Free-floating barrel eliminates handguard contact for consistent shot placement
• Upper receiver assembly can be used to retrofit compatible AR-style rifle platforms

Magazine not included.