Key Features
HK Gas Piston
Same piston-driven operation as the HK416. Eliminates hot carbon fouling in the receiver that plagues direct impingement rifles.
Cold Hammer Forged
German cannon-grade construction. Tested beyond 12,000 rounds in development — surpassing mil-spec barrel standards.
Fully Ambidextrous
Ambi safety, bolt release, and magazine release. 45-degree safety throw for fast, natural manipulation from either side.
Suppressor Ready
Concentric 1/2×28 muzzle threads and 2-position adjustable gas block. Dial it in for suppressed or unsuppressed fire.
The HK MR556 A4 is a high-performance, smooth-operating, flat-shooting, extremely durable firearm for the discerning operator. Aside from being semi-automatic only and running a heavy-profile match barrel, this is essentially the closest thing to a real HK416 you can get in the United States.
Where the HK416's barrel is thin-profile and chrome-lined, the MR556 A4's unlined barrel is optimized for precision. Don't let "unlined" fool you — it's a German cannon-grade cold hammer forged piece that surpassed mil-spec barrels during development, logging a verified 12,000-round count during testing.
Just like the real HK416, the MR556 A4 carries slim-line furniture with an M-LOK handguard and HK's proprietary gas piston operating system. A piston and solid operating "pusher" rod replace the conventional gas tube — virtually eliminating the malfunctions common to direct impingement because hot carbon fouling and waste gases never enter the receiver area. It's the same key feature critical to the HK416 rifles used by leading military and law enforcement customers worldwide.
Beyond the core operating system, every touchpoint on this rifle was engineered with purpose. The upper is HK416 A5 spec with a continuous picatinny rail interface running to the M-LOK handguard. Integral ambidextrous QD cups sit on both sides. The "over the beach" buffer tube includes drainage ports for water operations, and the reinforced double-length castle nut won't back out under sustained fire.
Every Touchpoint Engineered
- HK416 elongated steel castle nut
- HK416 A5 upper receiver
- Continuous picatinny rail upper-to-handguard
- M-LOK interface with integral ambi QD cups
- Suppressor-ready 1/2×28 concentric threads
- Match rifle cold hammer forged barrel
- Ambi safety, bolt release, magazine release
- 45-degree ambi safety selector throw
- Updated angled magazine well for reliable feeding
- HK416 2-position adjustable gas block
- "Over the beach" buffer tube with drainage ports
- Single point QD end plate
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