Brand: HK (Heckler & Koch)
Model: MR556 A4
Caliber: 5.56x45mm NATO
Action: Semi-Auto
Operating System: Gas Piston
Capacity: 30
Barrel Length: 11"
Barrel Description: Threaded
Thread Pattern: 5/8"x24
Barrel Material: Steel
Barrel Finish: Black
Twist Rate: 1:7"
Receiver Description: Picatinny Rail
Receiver Finish: Patriot Brown
Stock Type: 6-Position Adjustable
Stock Material: Synthetic
Grip: Black Polymer
Handguard: M-LOK
Trigger Pull Weight: 4.50 – 5.60 lbs
Safety: Ambidextrous Safety Lever
Sights: None (Optics Ready)
Overall Length: 26.50"
Height: 7.50"
Width: 3.07"
Weight: 6.61 lbs

Features

The HK MR556 A4 is a premium 5.56x45mm tactical pistol designed to military specifications and loaded with elite features. Built around HK’s legendary short-stroke gas piston system, this model reduces fouling and heat transfer into the receiver for unmatched reliability and cleaner operation during extended firing. Its cold hammer-forged 11" barrel with a 1:7” twist ensures excellent accuracy and barrel longevity, while the Patriot Brown finish offers a rugged, tactical look.

This pistol features a lightweight M-LOK handguard for versatile accessory mounting and ambidextrous controls—including the safety selector and charging handle—making it equally comfortable for right- and left-handed shooters. The 6-position adjustable synthetic stock provides a customizable, stable shooting platform in any situation. With a full-length Picatinny rail on the receiver, you have ample space to mount optics, iron sights, or lasers as you prefer. The smooth 4.5–5.6 lb trigger pull complements its sleek design, delivering exceptional control and battlefield-proven durability in a compact, civilian-legal package with a 30-round capacity.

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These items are controlled by the U.S. Government and authorized for export only to the country of ultimate destination for use by the ultimate consignee or end-user(s) herein identified. They may not be resold, transferred, or otherwise disposed of, to any other country or to any person other than the authorized ultimate consignee or end-user(s), either in their original form or after being incorporated into other items, without first obtaining approval from the U.S. government or as otherwise authorized by U.S. law and regulations.

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California 10+ Round Magazine Buyers: PSA values your freedom and constitutional rights above all else. However, PSA will not accept new orders nor will ship any order until the Ninth Circuit Federal Court of Appeals mandate becomes finalized. Once this mandate is finalized, we will start accepting new orders and ship 10+ round magazines to California Customers.

WARNING: Handling firearms or firearms parts can expose you to lead and other petroleum products known to the State of California to cause cancer, birth defects, or other reproductive harm. Wash hands thoroughly after handling. For more information go to www.p65warnings.ca.gov (CA Health and Safety Code Section 25249.6).