The 5.56x45mm is a small-caliber rifle cartridge commonly used by military and law enforcement agencies. It was developed in the 1960s and is known for its lightweight design and high velocity, making it effective for various shooting applications. The cartridge is often associated with the M16 and M4 rifles, which are standard-issue firearms for many armed forces. This cartridge features a bullet diameter of 5.56 mm and a case length of 45 mm. It is designed to be accurate at longer ranges while producing relatively low recoil, allowing for quicker follow-up shots. The 5.56x45mm is also popular among civilian shooters for sport and hunting purposes.