Heckler & Koch MR556 Semi-Automatic Rifle 5.56mm NATO 16.5" Barrel (1)-10Rd Magazine Synthetic Adjustable Stock Black Finish
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
Firearm Stock: Black Synthetic Adjustable
Features: Hellfighter MOD Kit
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: Medium Contour
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
