What is the difference between m1 and m2 carbine barrel?

Answer 1

The M1 carbine is a semi-automatic rifle meaning that with one pull of the trigger the rifle will fire one bullet.

The M2 carbine is a selective fire rifle meaning that there is a switch on the rifle which will select semi-automatic or fully-automatic fire. With fully automatic fire the weapon will continue firing as long as the trigger is pulled until the magazine is empty. This type of rifle is properly classified as an assault weapon. Both rifles share many common parts and barrels will interchange. The main mechanical difference is in the fire control parts. Possession of a certain number of unregistered M2 parts is considered by the BATF to be possession of an unlicensed machine gun and is a felony.