The 5.56×45mm is a small-caliber rifle cartridge primarily used by military forces around the world. It was developed in the 1960s and is known for its lightweight design, which allows soldiers to carry more ammunition. The cartridge is commonly associated with the M16 and M4 rifles, which are standard issue for many armed forces. This cartridge features a bullet diameter of 5.56 mm and a case length of 45 mm. It is designed for high velocity and low recoil, making it effective for both close-quarters combat and longer-range engagements. The 5.56×45mm is also popular among civilian shooters for sporting and recreational purposes.