Smith & Wesson M76, a variant of the Carl Gustav M/45 submachine gun
The Valmet M76, M72 and M78 have been used as props to simulate the AK-47 and related Soviet weapons in a number of US films during the Cold War, most notably Red Dawn, Commando and Firefox, most likely due to their availability.
The typical scope used is a ZRAK ON-M76 4x 5°10’ scope originally produced in the ZRAK factory in Sarajevo, Bosnia and Herzegovina.