HK USA MR556 5.56 NATO Complete Upper Receiver - 16" with Geissele HK416 Super Modular M-LOK Handguard Combo

Heckler & Koch MR556 A4 5.56 NATO Complete Upper Receiver Kit - 16"
51000384

Designed for standard AR-style rifles, the Heckler & Koch MR556 A4 Complete Upper Receiver Kit is a 5.56 NATO assembly featuring HK’s short-stroke gas piston system. This kit contains a 16-inch cold hammer forged barrel, a complete upper receiver featuring a forward assist, and an extended convertible charging handle. The HK Free Floating Rail System handguard offers a stable mounting platform and reduces barrel deflection. The HK416's operating system is incorporated into this upper, minimizing carbon buildup and enhancing its reliability. This upper kid also includes an MR556 bolt carrier group, a custom buffer system, an adjustable gas block, and a soft case for transport.

Features:

• 5.56 NATO complete upper receiver
• 16" cold hammer forged barrel
• 1:7 rate of twist
• Short-stroke gas piston system minimizes fouling
• HK Free Floating Rail System handguard
• Complete MR556 bolt group included
• Extended convertible charging handle
• HK proprietary tungsten-filled buffer and buffer spring
• Adjustable gas block for suppressed or unsuppressed use
• Includes HK-branded soft case

Geissele Automatics HK416 Super Modular M-LOK Handguard - Black - 14.5"
05-848B

The Geissele Automatics Super Modular Rail HK416 M-LOK is a 14.5-inch handguard designed for compatibility with HK416 and MR556 rifles. It installs using the factory HK barrel nut and is machined from 6061-T6 aluminum with a Type 3 hardcoat anodized finish for wear resistance. M-LOK slots span the 3, 6, and 9 o’clock positions, while a continuous Picatinny rail runs along the top for full accessory support. A 1.35-inch inner diameter offers space for low-profile components without unnecessary bulk. Weighing 14.2 ounces, this rail is optimized for 16-inch barrels. It is made in the USA.

Features:

• HK416 and MR556 handguard
• Length: 14.5-inches
• Optimized for 16-inch barrels
• M-LOK slots at 3, 6, and 9 o’clock positions
• Full-length Picatinny top railUses standard HK barrel nut for installation
• 6061-T6 aluminum construction
• Type 3 black hardcoat anodized finish
• 1.35-inch inner diameter
• Made in the USA