Ruger Security Six revolver with 4" barrel is Det. Jack Murphy's (Charles Bronson) service weapon. Joan Freeman (Carrie Snodgress) carries her own Security Six but in one scene she uses stolen Murphy's revolver.
During the escape from the LAPD building Murphy (Charles Bronson) takes a Smith & Wesson Model 10 from a police officer (later in this scene the revolver switches to Colt Trooper). S&W Model 10 revolvers are also seen in hands of various police officers and airport security guards. In one scene Arabella McGee (Kathleen Wilhoite) is armed with a S&W Model 10 that was taken from Max (Tony Montero), one of Frank Vincenzo's bodyguards.
Colt Trooper
During the escape from the LAPD building Murphy (Charles Bronson) is seen with a Smith & Wesson Model 10 that later switches to Colt Trooper. Later Murphy is again seen with a Colt Trooper that he takes from Jack (David Hayman), one of Frank Vincenzo's bodyguards.
Reese (Cal Haynes), one of Frank Vincenzo's bodyguards, carries a Heckler & Koch P9S pistol during the shootout in the hotel.
Heckler & Koch P7
Santana (Hans Howes), another one of Frank Vincenzo's bodyguards, carries a Heckler & Koch P7 during the shootout in the hotel and in the final scene.
Submachine Guns
Uzi
In the final scene Frank Vincenzo (Richard Romanus) is armed with an Uzi.
Shotguns
Ithaca 37
Various police officers are seen with Ithaca 37 shotguns.
High Standard Flite King
Sonny (Dennis Hayden), one of the three criminals on the drug farm, is armed with a High Standard Flite King shotgun. These shotguns are also seen in hands of police officers.
Remington Model 870
Kelly (Frank Annese), another one of the three criminals on the drug farm, is armed with a Remington Model 870 shotgun with sawn-off buttstock.
The last one of the three criminals on the drug farm (supposedly this character is Hog (Paul McCallum) but not for sure) is armed with an original M16. It can be identified due to its 3-prong flash hider. Murphy (Charles Bronson) disarmes this criminal and uses M16 himself.
Other Weapons
Crossbow
In the final scene Joan Freeman (Carrie Snodgress) is armed with a crossbow with a sniper scope.
Ben Wilcove's gun collection
Several old guns are seen in Ben Wilcove's (Bill Henderson) house.