Beretta M12 The Beretta Model 12 is a 9×19mm Parabellum caliber submachine gun designed by Beretta . The production started in 1962 , the first users were the Italian Carabinieri and the Italian State Police even though in limited number , only in 1978 it was widely issued replacing the old Beretta MAB . Oddly enough in 1962 the Italian Army bought a limited number of Franchi LF57 submachine gun , judged better than the M12 but never issued to the troops , and only in 1992 the M12S2 variant was introduced also if in very limited number . The Italian Air Force , instead , bought a large number of M12S and M12S2 for the airport security units . However the weapon had a higher initial success in the Arab countries and South America . Its debut in combat came during the Tet Offensive in 1968 when the Marines guarding the U . S . embassy in Saigon repelled the assault by the Viet Cong using the Beretta M12 . It is also used by various South American and African countries , and made under license in Brazil by Taurus and in Indonesia by PT Pindad . Development . In 1959 , Beretta weapons designer Domenico Salza revisited an old project , the Armaguerra Cremona OG44 submachine gun , in order to made a new submachine gun to replace the old MAB model 1938 . The Model 12 was the final production model , and was followed ten years later by the M12S with differences in the safety and other mechanics . Design details . The Model 12 weighs 3 . 48 kilograms empty ( about 3 . 820 kg loaded ) and is 660 millimeters in length with stock extended ( 418 mm when retracted ) . Its short length is achieved by use of a barrel recessed into the bolt head , known as a telescoping bolt . This reduces length without reducing barrel length or bolt weight . It fires from an open bolt and has a cyclic rate of fire of 550 rounds per minute . Its muzzle velocity is 380 meters per second . It is accurate to 200 / 300 meters . The barrel and rifling are chromium - plated to prevent fouling . The bolt housing has grooves to allow bolt movement , even in extremely adverse conditions such as exposure to mud , dust , or sand . The exterior surfaces of the firearm are finished with epoxy resin coating for protection against corrosion and damage . The weapon has a selective - fire option allowing a choice of single shot or fully automatic fire . The weapon has three safeties : a manual safety which blocks the trigger ; an automatic safety on the rear grip which immobilizes the trigger and blocks the bolt in a closed position ; and a safety on the cocking handle locking the bolt in case it does not retract sufficiently . The weapon is provided with a front sight ( adjustable for elevation and windage ) and a rear sight with a two - position flip aperture ( up to 100 m and up to 200 m ) . The gun is equipped with a side folding stock , but is also seen rarely with a fixed stock . Twenty , 32 , and 40 - round box magazines were available for the original Model 12 , which was chambered for the 9mm Parabellum cartridge . Variants . The first variant was introduced , in limited number , at the end of the ' 60s for the Italian Navy special forces and is easily recognizable from the longer barrel , about one inch , and the presence of a birdcage - type flash suppressor . It has been replaced by the H & K MP5 The Model 12 was redesigned as the Beretta Model 12s in 1978 . The Model 12s uses a 32 - round box magazine , and is chambered for the 9×19 mm NATO cartridge . A novel feature is the grip safety , which locks the trigger and the bolt in the closed position , thus safeguarding against accidental firing if the grip is not held firmly or if the gun is dropped . The safety and fire - selector switch , which in the original Model 12 were two separate push - pin button ( with the fire - selector being a button that activated single - fire or burst fire whether it was pushed on the right side or the left side ) have been re - engineered in a modern lever - type selector with three positions ( S for " Sicura " or Safety , 1 for Single - fire , R for " Raffica " or Burst fire ) . The fixed firing pin on the face of the bolt can strike the primer only when the cartridge is chambered fully , and this also avoids accidental firing , according to its designers . The PM12S was also designed with easy field - stripping and reassembly in mind , which has been simplified and can be accomplished without tools . It can be equipped with a suppressor , but this requires a slight modification of the barrel by a competent gunsmith . Minus the suppressor and other optional features , the Beretta PM12S is made up of 84 discrete components . The current version of the Beretta Model 12 , is called the PM12 - S2 In the mid - 1980s the Italian Carabinieri , after some tragic misfire accident , asked for a modification , in the form of a further safety device , which allowed both to keep the bolt of the weapon in half - cocked position and acted as an interceptor preventing accidental fire should the bolt or the firing pin suddenly disengage . This modification was implemented as a standard factory feature , and the denomination of the sub - machine gun changed to PM12 - S2 ; this is the only Model 12 variant currently manufactured by Beretta . The widespread Croatian Agram 2000 is based on the M12 .