Heckler & Koch MR556 A4 11″ Upper Receiver Features
Optimized for suppressed and CQB applications, the 11-inch MR556 A4 upper is built around HK’s short-stroke gas piston system with an adjustable gas block, enabling smooth function with or without a suppressor. The 1/2×28 threaded barrel is concentric and precision-machined, ensuring compatibility with muzzle devices and suppressors.
It includes a monolithic M-LOK handguard with integrated ambidextrous QD sling cups, a continuous Picatinny rail for optics and sights, and an ambidextrous charging handle with dual claw extensions. The match-grade cold hammer-forged barrel provides outstanding accuracy and barrel life, while the included bolt carrier group, charging handle, buffer weight, and buffer spring make this upper fully operational out of the box.
Heckler & Koch MR556 A4 11″ Upper Receiver Specifications
- Manufacturer: Heckler & Koch (HK)
- Model: MR556 A4 Upper Receiver
- Series: MR556
- Category: Uppers
- Caliber: .223 Remington / 5.56 NATO
- Barrel Length: 11″
- Thread Pattern: 1/2×28
- Firearm Fit: AR-15 Lower Receivers
- Handguard: M-LOK Interface with Integral Ambi QD Cups
- Rail: Continuous Picatinny (Upper to Handguard)
- Charging Handle: Extended Ambidextrous with Dual Claws
- Barrel Type: Match-Grade Cold Hammer-Forged
- Gas System: Adjustable Regulator (Suppressed/Unsuppressed)
- Finish: Anodized
- Color: Black
- Includes: Bolt Carrier Group, Charging Handle, Buffer Weight, Buffer Spring
| Barrel Length | 11 |
|---|---|
| Caliber | 5.56 |
| Condition | New in Box |
| Finish Per Color | Black |
| Manufacturer | Heckler and Koch |
| Manufacturer Part Number | 51000385 |
| Model | MR556 A4 Upper Receiver/Barrel Assembly |
| Type | Uppers |
| UPC | 642230270220 |
Frequently Asked Questions About This Product
Why buy Heckler and Koch MR556 A4 Upper Receiver/Barrel Assembly 5.56 11" Barrel 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 Upper Receiver/Barrel Assembly 5.56 11" Barrel?
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 Upper Receiver/Barrel Assembly 5.56 11" Barrel 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: New Arrivals, Uppers.
What tags or features does this product have?
Key features and tags for this product include: New Arrivals, Uppers.
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 Upper Receiver/Barrel Assembly 5.56 11" Barrel
All firearms, including the Heckler and Koch MR556 A4 Upper Receiver/Barrel Assembly 5.56 11" Barrel, 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 Upper Receiver/Barrel Assembly 5.56 11" Barrel 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.
