The Beretta M1938 submachine gun was designed by Beretta engineer Tulio Marengoni as an improvement on the earlier M1918 design (which was in turn based on the Villar Perosa). Developed during the mid 1930s, the initial variant (M38) was a high quality gun, and very reliable. Despite the tubular appearance, it used a milled receiver and was fairly expensive to manufacture – one of the last of the first generation SMG designs.
Mechanically, the M38 series was typical of submachine guns of its time, and not particularly innovative. However, it was a solid and well-made gun and developed a very good reputation. All variants had dual triggers; the front one for semiauto fire and the rear for full auto. Magazines were made in 10-, 20-, 30-, and 40-round capacity, double-stack and double-feed (meaning rounds alternated between being on the left and right, instead of being forced into a single column at the top of the magazine). All of the M38 family guns were chambered for 9mm Parabellum, and fired at 400-500 rounds per minute.
Somewhat unusual for this type of gun, the M38 has a charging handle on the right side of the receiver and the ejection port on the left side. It fires from an open bolt, and to ready the gun one pulls the charging handle back to bring the bolt back and then push the charging handle forward until it locks in place. This prevents dirt from entering the right side of the action, and the handle does not reciprocate during firing.
- M1938 – The first variant of the gun was the most complex. It used a small-diameter recoil spring captive inside a guide tube and had a removable firing pin. A small lever in the bolt engaged the front of the receiver to push the firing pin forward, preventing out of battery discharges. The M38 had a long wooden stock and a ventilated barrel shroud with a single large compensator port at the muzzle and a bayonet lug. It was manufactured only in 1938 and 1939.
- M1938A – Shortly after introduction, several small changes were made to the gun, and it was redesignated the M38A available in the US. The most visible change was the use of 4 small slots in the compensator and the removal of the bayonet lug. Both the M38 and 38A retained relatively expensive features like sliding magazine well covers and range-adjustable rear sights.
- M1938/42 – The 38/42 variant of the gun was put into production in 1943 to reduce manufacturing costs. The barrel shroud was removed, the stock cut down to end at the magazine well, the magazine cover removed, rear sight simplified to a fixed notch with a single long-range flip up notch, and the receiver redesigned as a stamping. Two compensator slots were cut in the top of the barrel at the muzzle. This model used a fixed firing pin in place of the safety system of the M38 and M38A. However, it did have a fluted barrel to reduce weight (it weighed 8lb, compared to 9lb 13oz for the M38A).
- M1938/43 – Shortly after introduction, the 38/42 was further simplified by using a smooth barrel instead of a fluted one.
- M1938/44 – The design was again modified to replace the captive small-diameter recoil spring with a larger diameter spring that was held in place simply by nesting around the rear of the bolt (much like a Sten gun).
- M1938/49 – Production continued for military and police contracts after World War II, and in 1949 the lever-type safety was replaced with a cross-bolt one.
- Model 4 – To divert attention from the age of the design, post-war guns made for export were given different model numbers. The Model 4 is actually just an M38/49.
- Model 5 – Identical to the Model 4, but with the addition of a grip safety in the finger grooves of the stock. Production of the Model 4 and 5 continued until 1962, and guns remained in Italian military service into the 1980s.