While with his cousin, Carlito Brigante (Al Pacino) takes a nickel plated M1911A1 with pearl grips from one of the thug's waistband to shoot his way out of the bad drug deal. If you look closely at Carlito's nickel 1911 in some scenes, you can see that it has a 9mm caliber barrel and magazine, which was likely used because .45 blanks don't cycle well. It also has a beveled magazine well.
One of the thugs Carlito shoots at the bad drug deal manages to fire his Smith & Wesson Model 10 which is snub nosed and nickel plated. One of the Italians uses one in the final shootout as well.
Carlito Brigante (Al Pacino) uses a Beretta 92F with the finish worn off the end of the barrel as his personal weapon for the rest of the film. This is an anachronism as the film takes place in 1975.
David Kleinfeld (Sean Penn) uses a nickel-plated Smith & Wesson Model 36 with pearl grips as his personal weapon. Vincent Taglialucci (Joseph Siravo) also uses a suppressed version and Pete Amadesso (Richard Loronjy), one of Vincent's friends, also uses one in the final shootout.
The officers on the subway carry Ruger Security Six revolvers as their sidearms. The grips are missing the Ruger emblem and look like plastic and not wood. The finish is also not glossy which leads one to believe that the gun is fake.
During the bar shotout Quisqueya (Rick Aviles) shoots at Carlito (Al Pacino) with a unknown handgun.
Benny Blanco (John Leguizamo) also uses an unknown suppressed pistol.
