The M2 carbine is a version of the M1 carbine, a lightweight .30 caliber submachine gun developed in the 1940s. Easy to use, the M1 carbine was widely used by military and civilians alike.
The M2 carbine is a selective fire version of the M1 carbine. It is capable of firing in semi-automatic or fully automatic modes through a selector switch. The selective fire feature of the M2 carbine is the only significant difference between the M1 and M2.