Beretta M1918

The Beretta Model 1918 was a submachine gun that entered service in 1918 with the Italian armed forces. Designed initially as a semi-automatic rifle, the weapon came with an overhead inserted magazine, an unconventional design based on the simplicity of allowing a spent round to be replaced using assistance from gravity. The gun was made from half of a Villar-Perosa aircraft submachine gun, and as such it can be considered the first submachine gun issued to and used by the Italian armed forces, and is possibly the first SMG used as a general-issue combat weapon. Certain sources say that it saw service a few weeks before the German MP 18; the exact date remains debated.
Another variant was the semiautomatic Model 1918/30 with the magazine inserted underneath and came with a bayonet. The Model 1918/30 was also manufactured in Argentina by Hafdasa as the C-1, which formed the basis of the Ballester-Riguard submachine gun.