The Godfather Part III is the third and final installment in the film saga of the Corleone crime family that began with 1972's The Godfather and continued with 1974's The Godfather Part II. The film follows Michael Corleone (Al Pacino) as he attempts to put his criminal background behind him by going into business with the Vatican.
The following firearms can be seen in the film The Godfather Part III:
Vincent Mancini (Andy Garcia) pulls a Beretta Cheetah when confronted by assassins sent by Joey Zasa (Although the pistol turns into a Walther PP for a close-up).
Walther PP
For the close-up in which Vincent shoots the thug through the head, an Walther PP replaces the Beretta Cheetah. Al Neri (Richard Bright) is also given a Walther PP hidden in a box of cookies while on the train to meet Archbishop Gilday.
Colt Police Positive
While dressed as an NYPD officer on horseback, Vincent Mancini (Andy Garcia) uses a Colt Police Positive to shoot Joey Zasa.
Several 12 Gauge Double Barreled Shotguns with exposed hammers can be seen. Al Neri (Richard Bright) uses one to blast out of the Atlantic City meeting, one of Vincent's hitmen uses one during the street parade shooting, Mosca (Mario Donatone) uses one when shooting at Don Tommasino's car, and some of the actors during Anthony's opera in Sicily can be seen handling some.
Submachine Guns
IMI Uzi
The helicopter hitmen sent by Joey Zasa (Joe Mantegna) to kill Michael Corleone (Al Pacino) and other mob bosses at the Atlantic City meeting carry Uzi submachine guns.
MAC-10
One of Vincent's hitmen during the street parade hit carries a MAC-10.