5.56 NATO / .223 REM

The 5.56×45mm NATO is an intermediate, bottlenecked rifle cartridge featuring a .224-inch diameter projectile. Standardized by NATO in 1980 and derived from the civilian .223 Remington, it is widely used in military service and modern sporting rifles like the AR-15 for its low recoil, high velocity, and flat trajectory.

Core SpecificationsMuzzle Velocity: ~2,700 to 3,300 feet per second (depending on barrel length and load)

Effective Range: Up to approximately 500 yards (450 meters) for standard infantry applications

Base Case: Rimless, bottlenecked centerfire

Compatibility: Highly similar to .223 Remington, though 5.56 NATO generates higher chamber pressures
Common Bullet Weights & Types55-Grain (M193): The standard lightweight, high-velocity round ideal for general training, target shooting, and plinking.
62-Grain (M855 / "Green Tip"): The traditional NATO military load featuring a steel penetrator tip designed for improved barrier performance.
69 to 77-Grain: Heavier match-grade and open-tip loads preferred for long-range precision shooting, competitive matches, and defense