Heckler & Koch HK MR556 A4 13.4" M-LOK Free-Float Handguard - Black - 51001176
Product Description
The Heckler & Koch 51001176 is an authentic factory HK MR556 A4 13.4-inch extended handguard engineered for HK MR556, HK416, and compatible short-stroke gas piston rifle upper receivers. Designed as a direct drop-in modular front rail upgrade, this handguard provides extended handguard real estate and modern accessory mounting flexibility while shedding unnecessary weight compared to legacy quad-rail systems.
Precision-machined from high-strength, aircraft-grade aluminum alloy and finished in a matte black hardcoat anodize, the 13.4-inch MR556 A4 handguard features a full-length continuous top MIL-STD-1913 Picatinny rail for seamless alignment with upper receiver optics and laser aiming devices. Integrated M-LOK attachment slots positioned along the 3, 6, and 9 o'clock positions allow low-profile mounting of weapon lights, vertical foregrips, barricade stops, and bipods. It also incorporates dual-sided quick-detach (QD) sling swivel sockets near the receiver junction for rapid sling attachment.
Utilizing HK’s robust cross-bolt locking mechanism, the handguard secures firmly over standard HK barrel nuts without requiring proprietary upper modifications. Its slim ergonomic profile offers superior barrel heat dissipation and a comfortable c-clamp shooting grip, making it an essential component for staging modern, tactical MR556 or HK416 rifle configurations.
*Armorer Bench Notes & Real-World Staging Guidance:
Platform & Barrel Nut Compatibility Matrix:
• Primary Compatibility: HK MR556 A1/A3/A4 series, HK416 (D/14.5"/16" barrel configurations), and civilian HK416 clones utilizing factory HK barrel nut geometry.
• Gas System Fitment: Fits over standard short-stroke gas piston assemblies and adjustable gas blocks.
Installation & Staging Steps:
1. Clear host rifle, verify chamber is empty, and remove existing handguard by unscrewing the single cross-locking screw using an HK armorer wrench or 11mm socket.
2. Slide the 51001176 handguard rearward over the barrel and short-stroke gas piston assembly until fully seated flush against the upper receiver receiver rail bridge.
3. Insert the steel cross-bolt through the handguard retaining channel and barrel nut groove.
4. Torque the cross-bolt to factory specification (approx. 45 in-lbs) to ensure a rigid, zero-slop return-to-zero foundation for laser designators and front iron sights.
Key Features
- Genuine Heckler & Koch factory MR556 A4 13.4-inch free-float handguard.
- Full-length top MIL-STD-1913 Picatinny rail seamlessly aligns with upper receiver rail height.
- M-LOK accessory attachment slots at 3, 6, and 9 o'clock positions for modular accessory mounting.
- Integrated quick-detach (QD) sling swivel mounting sockets on left and right sides.
- Machined from high-grade aluminum with a durable matte black hardcoat anodized finish.
- Slim, ergonomic profile reduces overall front-end weight while enhancing heat dissipation.
- Secures using HK's proven heavy-duty single cross-bolt attachment mechanism.
- Made in Germany by Heckler & Koch.
Product Specifications
- Brand: Heckler & Koch (HK)
- MPN / Model: 51001176 / MR556 A4 13.4" Handguard
- Length: 13.4 Inches
- Attachment Interface: M-LOK & MIL-STD-1913 Picatinny
- Material: Aircraft-Grade Machined Aluminum
- Finish: Matte Black Hardcoat Anodized
- Platform Fitment: HK MR556 / HK416 / HK CR556 Series
- Mass: Approx. 0.92 lbs (14.72 oz)
