FIAT-Revelli submachine gun

In December 1916, the Italian Test Commission observed the demonstration of a new weapon known as the Moschetto Automatico Revelli. This gun had been commissioned by the Air Artillery Corps, presumably for use as an automatic carbine by pilots or aerial observers, and was developed jointly by FIAT of Turin and RIV of Pinerolo, with the design work being attributed to Col. Abiel Revelli. The FIAT/Revelli "automatic musket" was essentially a conversion of the twin-barreled Villar Perosa 9mm machine-gun into a single-barreled, shoulder-fired carbine by installing a single Villar Perosa receiver onto a wooden stock and fitting it with a conventional trigger group. Everything about the delayed-blowback action was unchanged and the overhead 25-round magazine feed was retained. The design was improved, however, by the addition of a fire selector switch which gave automatic fire and single shots. Other modifications were entirely external. When the bolt was in the closed position, the bolt handle would sit in a metal cup which it was lifted out of by a retracting lever similar to that of the Villar Perosa's. The downward-facing ejection port was fitted with a curved case deflector which would redirect the spent casings forward of the firer.

Further tests took place in February of 1917. The gun was only a rough prototype in its current state but the concept showed considerable promise and the Italian Army expressed interest in seeing it developed further. By March, Revelli had revised the design into an embryonic form of the later O.V.P. submachine gun. Meanwhile the Army commissioned several other firms to produce similar conversions of the Villar Perosa for evaluation, which resulted in prototype SMGs from Ansaldo, Beretta, SIAI Savoia, A.N., and Cei-Rigotti. The FIAT/Revelli weapon, however, can lay claim to being one of the first "true" submachine guns in history.