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Heckler and Koch MR556 A4 Patriot Brown 5.56 16.5″ Barrel 10-Rounds

~~$3,591.99~~ $3,232.79

The HK MR556 A4 is a precision-engineered tactical rifle chambered in 5.56x45mm, featuring a 16.5-inch threaded barrel, Patriot Brown anodized receiver, and a 10+1 round capacity for compliance with restrictive states. Based on the renowned HK416, this rifle uses a short-stroke gas piston operating system that reduces fouling and heat transfer, resulting in cleaner and more reliable performance under high-volume fire. Its ergonomic 6-position adjustable stock, ambidextrous controls, and black M-LOK handguard provide modern adaptability and user comfort in any environment.

Description

HK MR556 A4 Features

This rifle incorporates a cold hammer-forged steel barrel with a 1:7″ twist rate and six-groove rifling, offering durability and precision for a variety of bullet weights. The threaded muzzle with a 5/8×24 pattern allows for easy suppressor or muzzle device installation, while the full-length Picatinny rail provides optimal optic placement and accessory attachment. The trigger pull weight, ranging from 4.5 to 5.6 pounds, ensures smooth and consistent operation.

The MR556 A4 is engineered with an ambidextrous safety, making it ideal for both left- and right-handed shooters. The rifle also features a robust polymer stock and grip, paired with a durable anodized handguard that supports accessories through the M-LOK interface. Whether for precision shooting or tactical use, the MR556 stands out as a versatile and rugged option.

HK MR556 A4 Specifications

Brand: HK
Model: MR556
Series: A4
Category: Tactical Rifles
Caliber: 5.56x45mm
Action: Semi-Auto
Operating System: Gas Piston
Capacity: 10 + 1
Max Capacity: 10
Barrel Length: 16.5″
Barrel Description: Threaded
Barrel Material: Steel
Barrel Finish: Black
Twist Rate: 1:7″
Grooves: 6
Thread Pattern: 5/8″x24
Muzzle: Threaded
Receiver Description: Picatinny Rail
Receiver Finish: Patriot Brown
Receiver Material: Aluminum
Handguards: M-LOK
Handguard Finish: Black
Stock Description: 6 Position
Stock Material: Synthetic
Stock Finish: Black
Overall Length: 36.5″
Height: 7.5″
Width: 3.07″
Weight: 7.67 lbs
Trigger Pull Weight: 4.50-5.60 lbs
Safety: Ambidextrous Safety Lever
Sights: None
Hand: Ambidextrous

More Information
Barrel Length	16.5
Caliber	5.56
Capacity	10
Condition	New in Box
Finish Per Color	Patriot Brown
Manufacturer	Heckler and Koch
Manufacturer Part Number	81001204
Model	MR556 A4
Type	Modern Sporting Rifles
UPC	642230271081

Frequently Asked Questions About This Product

Why buy Heckler and Koch MR556 A4 Patriot Brown 5.56 16.5" Barrel 10-Rounds from Miami Shooters Supply?

We’re a trusted firearms dealer offering fast shipping, competitive pricing, and 100% compliance with U.S. federal firearm laws. All orders ship from our licensed facility with full tracking and expert customer service.

Where can I buy Heckler and Koch MR556 A4 Patriot Brown 5.56 16.5" Barrel 10-Rounds?

You can purchase this item directly on our website and have it shipped to your local FFL dealer. You can also visit us in-store in Miami, Florida.

Is Heckler and Koch MR556 A4 Patriot Brown 5.56 16.5" Barrel 10-Rounds available now?

Availability is shown live on this page. If the “Add to Cart” button is visible, this item is currently in stock and ready to ship.

What category does this product belong to?

This product is listed under: Modern Sporting Rifles, New Arrivals.

What tags or features does this product have?

Key features and tags for this product include: Modern Sporting Rifles, New Arrivals.

Is this product legal in my state?

It is your responsibility to ensure this item is legal in your state or locality. We ship only to valid FFL dealers in compliance with U.S. laws. Always check your local regulations.

FFL Transfer & Firearms Laws for Heckler and Koch MR556 A4 Patriot Brown 5.56 16.5" Barrel 10-Rounds

All firearms, including the Heckler and Koch MR556 A4 Patriot Brown 5.56 16.5" Barrel 10-Rounds, must be shipped to a licensed Federal Firearms License (FFL) dealer. You will be required to complete a background check and any necessary paperwork before taking possession.

How It Works

Place your order online.
Provide your preferred FFL dealer information.
We ship the firearm directly to your FFL.
You complete the background check and pickup at the FFL.

Legal Compliance

We comply with all federal and state firearm laws. It is your responsibility to ensure the Heckler and Koch MR556 A4 Patriot Brown 5.56 16.5" Barrel 10-Rounds is legal in your state. Some states may have restrictions on certain firearm models or features.

Helpful Resources

Need assistance? Contact our Miami store for help with FFL transfers and firearm compliance.

FFL & Firearm Laws
FFL Transfer & Firearms Laws

All firearms, including the Heckler and Koch MR556 A4 Patriot Brown 5.56 16.5" Barrel 10-Rounds, must be shipped to a licensed Federal Firearms License (FFL) dealer. A background check and any required local paperwork must be completed before you can take possession.

How It Works
1. Place your order online.
2. Send us your preferred local FFL dealer info.
3. We ship the firearm to your FFL after verification.
4. Complete background check and pick up from your dealer.
Legal Compliance

We comply with all U.S. firearm laws. It is your responsibility to ensure the Heckler and Koch MR556 A4 Patriot Brown 5.56 16.5" Barrel 10-Rounds is legal in your state. Some states (e.g. CA, NY, NJ) have restrictions on magazine size or certain features.

Helpful Links
Need help? Contact our team — we’ll guide you through selecting a compliant firearm and the FFL transfer process.