The M1 carbine (formally the United States Carbine, Caliber .30, M1) is a lightweight, easy to use, .30 caliber semi-automatic carbine that became a standard firearm for the U.S. military during World War II, and continued to be used throughout the Korean War and well into the Vietnam War. The M1 carbine was produced in several variants and was widely used by not only the U.S. military, but by military, paramilitary and police forces around the world. It has also been a popular civilian firearm.
The M2 carbine is the selective-fire version of the M1 carbine capable of firing in both semi-automtic and full-automatic. The M3 carbine was an M2 carbine with an active infrared scope system.
Despite its name, the M1 carbine is not a shorter version of the M1 Garand rifle. It is a completely different firearm and it fires a different type of ammunition. It was simply called a carbine because it is smaller and lighter than the Garand. On July 1, 1925, the U.S. Army began using the current naming system where the "M" is the designation for Model and the "number" represents the sequential development of equipment and weapons. Therefore, the "M1 rifle" was the first rifle developed under this system. The "M1 carbine" was the first carbine developed under this system. The "M2 carbine" was the second carbine developed under the system, etc.