The weapon was first seen during the Tet Offensive in 1968 when the U.S. 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,[5] 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).

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.

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).

This modification was implemented as a standard factory feature, and the denomination of the submachine gun changed to PM12-S2; this is the only Model 12 variant currently manufactured by Beretta.