Therein, however, lies the controversy: can a fully-automatic “carbine” properly be described as an assault “rifle”? The M2 was a simple modification of the ubiquitous M1 Carbine.

The M2 Carbine would remain in U.S. military service into the 1960s, even as the Army adopted the large M14 battle rifle and then the iconic M16 assault rifle still in use today.

Carbine vs rifle is like saying compact car vs automobile. A carbine is a rifle, but what exactly makes it a carbine? Here's the full answer.