When was the first 50 caliber used?

The first .50 caliber round, known as the .50 BMG (Browning Machine Gun), was developed during World War I in 1918 for the Browning M1917 machine gun. It was designed by John Browning and became widely used by the U.S. military in the following decades, particularly in World War II and beyond. The .50 BMG has since been utilized in various applications, including anti-materiel rifles and heavy machine guns.