The M3 field modification is the result of field workshop efforts to modify the standard M3 Grease gun. The standard M3 cocking handle has been removed, a channel has been cut into the receiver, and an improvised cocking handle has been added to the bolt. This compact weapon variant was developed to provide light and mobile firepower to American troops, particularly in close combat and tight quarters. The weapon utilizes 30-round magazines of .45 ACP caliber.

The M1918 Beretta is a sub-machine gun developed in Italy at the end of World War I. It became one of the first weapons of its class to be adopted. Essentially, it is a cut-down version of the Villar-Perosa M1915 aviation machine gun combined with the stock of the Parravicino-Carcano carbine. The M1918 Beretta is characterized by its simple design, reliability, and high rate of fire – up to 900 rounds per minute. The weapon uses 25-round magazines of 9mm caliber.