How a Beretta M12 SMG Works | World of Guns | Beretta PM-12S Operation and Field Strip

Wikipedia: The Beretta M12 (Model 12) is a 9×19mm Parabellum caliber submachine gun designed by Beretta. Production started in 1959, the first users were the Italian Carabinieri, Italian State Police and the Guardia di Finanza, though in limited number, it was only widely issued beginning in 1978, replacing the old Beretta MAB. In 1962 the Italian Army bought a limited number of Franchi LF-57 submachine guns, judged better than the M12 but never issued to the troops, and only in 1992 the M12S2 variant was introduced, in very limited number. The Italian Air Force, instead bought many M12S and M12S2 for the airport security units. However the weapon had a higher initial success in the Arab countries and South America.

The weapon was first seen during the Tet Offensive in 1968 when the US 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, African and Asian countries,[4] and made under licence in Brazil by Taurus, in Belgium by FN Herstal and in Indonesia by PT Pindad.

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.[5] It fires from an open bolt and has a cyclic rate of fire of 550 rounds per minute.

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.[6] 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.

20-, 32-, and 40-round box magazines were available for the original Model 12, which was chambered for the 9mm Parabellum cartridge.