The 5.56 NATO is a small-caliber, high-velocity cartridge primarily used by military forces around the world. It was developed in the 1950s and is known for its lightweight design, making it suitable for automatic and semi-automatic firearms. The cartridge is often used in rifles like the M16 and M4, providing effective range and accuracy. This cartridge is characterized by its 5.56 mm bullet diameter and typically uses a 62-grain projectile. The NATO designation indicates that it meets the standards set by the North Atlantic Treaty Organization, allowing interoperability among member nations' armed forces.