The HK MR556 A4 is a semi-automatic, short-stroke gas piston rifle built from the HK416-style upper platform, chambered in 5.56 NATO. This A4 configuration features a 16.5 inch barrel, an M-LOK handguard, and a collapsible/folding-style stock for adjustable handling. With a 1/2×28 threaded barrel and an ambidextrous manual safety selector, it’s designed for modern accessory and optic setups while being supplied with no sights included.
Key Features
Short-stroke gas piston semi-automatic operating system
16.5 inch barrel chambered in 5.56 NATO
1/2×28 threaded barrel for compatibility with common muzzle devices
10+1 capacity with included 10 rd magazine capacity configuration
Ambidextrous manual safety selector and fully ambidextrous lower controls
M-LOK handguard for lightweight, modular accessory mounting
If you’re looking for an HK MR556 A4 in a compact 16.5 inch configuration with a threaded muzzle and modern handguard system, this is a strong choice for building your ideal setup.
