The Beretta M1918 submachine gun (also known as Moschetto Automatico Beretta m1918) can be considered to be the first "conventional" submachine gun to be ever issued to the troops, as, according to some sources, its issue predates that of the more famous Bergmann Schmeisser MP-18 submachine gun by several weeks. It was designed on request from Italian army, which sought to improve on the cumbersome Villar-Perosa M1915 weapon. Beretta's designer Tulio Marengone took the half (one gun of the twin weapon) of the Villar-Perosa M1915 as a base, put it into the carbine-type wooden stock, and added rifle-type trigger unit. The barrel was lengthened and fitted with integral underfolding bayonet, making this gun a formidable "trench warfare" tool. It was reported as durable and reliable weapon, and more than few Beretta M1918 submachine guns survived to see the action during early stages of WW2, mostly in northern Africa.
The Beretta M1918 submachine gun uses delayed blowback action, in which the delay of the initial opening of the bolt is achieved by rotation of the bolt, through the bolt handle that slides against the inclined part of the cocking handle slot. Firing is from open bolt, in full automatic mode only. Feed is from top-mounted box magazine, ejection is to the bottom. An ejection chute is added to the bottom of the stock to protect firer's left handle from hot spent cases, which are ejected from the gun with considerable force. The sights are offset to the left to clear the overhead magazine. The muzzle is fitted with integral folding bayonet.