Despite have a long distinguished firearms heritage, Italian smallarms makers during World War II seemed to have floundered in attempts to make the next great advance in weapons designs. They came close quite often, but inevitably fell short when finding that right next generation weapon. And while other weapons makers were utilizing standard methods of operation for their rifles and submachine guns, Italian designers took an unusual route in their expertly built FNAB-43.
Only 7,000 of these 9mm Parabellum submachine guns were built during World War II and most of them confined to the Northern Italy front of 1943-1944. A folding-stock SMG, the FNAB-43 had a front pivoting magazine well to reduce the overall sihlouette of the weapon with a magazine inserted. The Italian SMG could take a 20 or 40-round magazine that would be spent at a relatively low, controlable rate of fire.
At 400 rounds per-minute, the FNAB-43 could put a steady, slow string of bullets. This rate of fire was not accplished by traditional methods of a heavy bolt or recoil springs, but rather lever-delayed blowback. The bolt assembly on the FNAB-43 had a bolt head and a small lever piece between it and the bolt body. As the bolt head recoiled slightly upon firing of the round, the lever would apply mechanical friction, slowing the rearward progress of the entire bolt assembly until it was unlocked when propellant gas levels reduced to safe levels.
A perfectly effective submachine gun, the FNAB-43 suffered from timing as Facist Italy fell war-time production staggered making the precision construction of the FNAB-43 unattainable.