Heckler & Koch MR556A1 Semi-Automatic Rifle 5.56mm NATO 16.5" Barrel (1)-10Rd Magazine Synthetic Adjustable Stock Black Finish
A direct descendant of the world-famous HK416, the MR556A1 is the commercial carbine from the same DNA. It offers the battlefield-proven reliability, durability and precision you would expect from a rifle that bears the name Heckler & Koch.
The MR556A1 is assembled in the USA using US and German-made components and uses many of the same parts and assemblies developed for the HK416.
Like the HK416, the MR556A1 uses a proprietary HK short-stroke gas piston in place of the direct-gas-impingement system found on lesser AR15-style rifles that propels exhaust gas into the upper receiver to operate the action.
In the “closed” HK piston system, exhaust gasses never enter the receiver, which means the HK runs cooler, cleaner and more reliably.
When adverse conditions, like dust, sand and mud are introduced, the advantage of the HK system becomes even more drastic. That is why so many of the world’s elite military and law-enforcement customers have absolute trust in their HKs.
The MR556A1’s barrel is cold hammer forged from the highest quality cannon-grade steel. It has a 1 in 7” twist and a taper-bore configuration, with a slightly smaller diameter at the muzzle for improved accuracy and velocity. And while the material and cold hammer forging process themselves greatly enhance durability, HK’s processes include many additional steps not taken by other manufacturers to produce superior accuracy and service life, ensuring performance well beyond “mil-spec.”
Type: Rifle: Semi Automatic
Model Series: MR556
Caliber/Gauge: 5.56 NATO
Capacity: 10+1
Barrel Length: 16.5 in.
Minimum/Overall Length: 37.68 in.
Safety: Manual Safety
Frame Finish: Black
Front Sight: Troy Micro
Rear Sight: Troy Micro
Firearm Stock: Black Synthetic Adjustable
Features: M-LOK Handguard
Finish: Black
Magazine Count: 1
Operating System: Gas Piston
Firing System: Internal Hammer
Scope Base: Picatinny Rail
Trigger: 2-Stage
Magazine Type: Double Stack Magazine
Barrel Configuration: Single
Barrel Description: Cold Hammer-forged
Muzzle: Flash Hider
Threaded Barrel: Yes
Rifled Barrel: Yes
Forend Rail: Free Float 4 Quadrant Rail
Caliber Dictionary
The Below Information Has Been Provided From Our Gun Caliber Dictionary And Is Meant For Informational Purposes Only. It Is Not Intended to Describe The Unique Specifications For This Ammunition.
The 5.56X45mm NATO cartridge was designed by James Sullivan, a member of Eugene Stoner's engineering team that developed both the M16 rifle and its original cartridge. The 5.56X45mm NATO was adopted by the U.S. military in 1964 and by NATO in 1980. With bullet diameter of .224-inch, the original M193 military cartridge used a 55-grain bullet at 3250 fps; the current M855A1 cartridge, developed by FN, uses a 62.5-grain bullet at 3020 fps, offering greater range and better penetration. The civilian version of the 5.56X45mm is 223 Remington; the cartridges are dimensionally identical but military chamber dimensions and specifications for military brass are different. It is considered safe to use 223 Remington ammo in a 5.56X45MM NATO chamber, but not a good idea to use 5.56X45mm ammo in a rifle specifically chambered for the 223 Remington. Although the stopping power of .22-caliber bullets remains controversial the 5.56X45mm has served well in now multiple generations of M16 rifles. — Craig Boddington
