Shotgun XM1014 The Benelli M4 is a semi automatic shotgun produced by Italian firearm manufacturer Benelli Armi SpA and the fourth and last model of the Benelli Super 90 line of semi automatic shotguns. The M4 uses a proprietary action design called the auto regulating gas operated ARGO system which was created specifically for the weapon. Designed in 1998 the M4 was adopted by the armed forces of Italy the United States and United Kingdom among others and has been used in a variety of conflicts.