The following weapons were used in the film Saw III:
Jeff (Angus Macfadyen) locates a Beretta 92FS and one round through the course of the game and ends up using it to shoot and kill Amanda. In shots where the gun is simply being carried, the Beretta is an airsoft prop, likely for safety and convenience reasons.
Smith & Wesson Model 5946
Eric Matthews (Donnie Wahlberg) has his Smith & Wesson 5946 from the previous film in this film's opening after waking up in the bathroom, only to discover that the magazine is empty. Later Amanda (Shawnee Smith) is armed with it and uses it to threaten Lynn frequently before ultimately shooting her with it. When Amanda fires it, it sounds as though it is suppressed
Smith & Wesson Model 10 HB
In a flashback, we see Jeff (Angus Macfadyen) in a state of anger over the death of his son pointing his personal Smith & Wesson Model 10 in the mirror imagining a confrontation between him and the man who hit his son with a car.
Smith & Wesson Model 686
In another flashback, we see John Kramer/Jigsaw (Tobin Bell) setting up the scenario from the first Saw. He has the Smith & Wesson Model 686 in his hand as he lays down as he appeared in the first movie.
Detective Allison Kerry (Dina Meyer) pulls a SIG-Sauer P226 from her nightstand when she suspects that Jigsaw is in her closet, she then fires a few shots through the closet door before being kidnapped.
Heckler & Koch MP5A3
The Heckler & Koch MP5A3 9mm SMG equipped with tactical lights and laser sights can be seen in the hands of the SWAT team breaching a welded shut door in the abandoned school to discover a man who has been a victim of a Jigsaw trap.
Heckler & Koch UMP
Unknown Double-barrel 12 Gauge
This 12 Gauge shotgun is seen in one of Jigsaw's traps and blows the face off Judge Halden when Jeff (Angus Macfadyen) retrieves the key that is tied to the trigger of it.