FIRING THE M1 CARBINE. The M1 carbine (formally the United States Carbine, Caliber .30, M1) is a lightweight semi-automatic carbine that was a standard firearm for the U.S. military during World War II, the Korean War and the Vietnam War. Despite having a similar name and physical outward appearance, the M1 carbine is not a carbine version of the M1 Garand rifle. On July 1, 1925, the U.S. Army began using the current naming convention where the "M" is the designation for "Model" and the number r