The Terminator (Arnold Schwarzenegger) acquires an AMT Hardballer Longslide with a primitive laserlock sight (a one-off made by someone from a company that would later become SureFire) in addition to several other weapons from a gunshop shortly after his arrival from 2029. He first uses it to assassinate two women from a phone book who share the name Sarah Connor. When he arrives at the real Connor's (Linda Hamilton) apartment, he uses it to kill her friend, Ginger Ventura (Bess Motta). Upon tracking Sarah to the Tech Noir nightclub, the Terminator loses this weapon when Kyle Reese (Michael Biehn) intervenes in his assassination attempt, at which point he switches to his IMI Uzi.
IMI Uzi
Another weapon the Terminator acquires from the Gun Shop at the start of the film is an IMI Uzi 9mm Carbine. In the sequence the gun store has the weapon on display with the short dummy barrel installed, which was done sometimes to entice buyers, however the Uzi Model A or B was always sold with a 16" barrel for legality. James Cameron mentioned in the magazine "Soldier of Fortune" that he assumed that the Terminator had converted the Uzi and the AR-180 into full auto weapons in his hotel room (which included sawing down the 16" barrel of the Uzi). He uses it mainly in the Tech Noir nightclub, when Kyle Reese (Michael Biehn) interferes with his attempts to terminate Sarah Connor (Linda Hamilton). After losing his .45, the Terminator unloads several rounds at the nightclub, killing quite a few innocent bystanders, but fails to hit Sarah, or Kyle. He loses the weapon when Kyle shoots him out of the club's window.
SPAS-12
Another gun used by the Terminator, is the Franchi SPAS-12 shotgun. The Terminator uses it to kill the gun store owner at the start of the film. Later, it is one of the two weapons he uses during the assault on the police station. A SPAS-12 is also seen in the hands of a human Resistance fighter in one of the "Future War" flashbacks. The SPAS-12's top folding stock was removed by the Terminator before the attack at the police station, presumably since a Terminator would not need the stock for recoil or stability. Schwarzenegger fired the SPAS-12 with one hand, displaying the 'strength' of the Cyborg. Trivia Note: A sound editing goof can be heard where the shotgun is made to sound like an assault rifle several times during the same scene.
AR-18
Yet another of the Terminator's guns is an Armalite AR-18 assault rifle. The gun is used without the stock (like the SPAS-12) and with two magazines taped together in a 'jungle style' configuration. He uses it primarily during the assault on the police station and during the car chase following the motel scene. The script refers to the rifle as an AR-18, however the rifle he picks up at the gun store is supposed to be the civilian (semi auto only) AR-180 model. The Terminator novel refers to the T-800 converting the rifle from semi to full auto using tools stolen from a hardware store earlier in the day. Of course the movie used a full auto rifle at all times, but no one should assume that people can buy full auto firearms over the counter in any gun store in California.
Smith & Wesson Model 15
After Kyle and Sarah are apprehended by the police later on, several officers can be seen holding Smith & Wesson Model 15s. Several officers also use Smith & Wesson Model 15 when the Terminator raids the police station. A nickel-plated Smith & Wesson Model 15 is also seen being wielded by the Terminator when he runs out of ammunition for his AR-18 during the car chase at the end.
Colt Trooper
Soon after arriving, Kyle Reese (Michael Biehn) grabs a Colt Trooper from a police officer and holds him at gunpoint while demanding to be told the current date, then flees into a nearby department store when more police arrive.
In that scene, the revolver resembles more closely a Smith & Wesson model 15 "Combat Masterpiece", as the typical S&W thumbpiece can be seen. On a S&W it has to be pushed forward rather than pushed backwards to unlock the cylinder, as is the case with a Colt double-action revolver.
Colt Python
Seen in the hands of a Police Officer that searches the patrol car that the Terminator abandoned.
Ithaca 37 Sawed Off
Soon after arriving, Reese procures an Ithaca 37 shotgun from an unattended police car. In addition to having a high-capacity magazine tube, Reese saws off part of the stock to give it a pistol grip instead making it easier to conceal under his trenchcoat. He notably uses it against the Terminator in the Tech Noir nightclub shootout, and the ensuing carchase after he and Sarah escape the car garage. Between acquiring the Ithaca and discharging it for the first time in the night club, Reese pumps the handle three times. First when he saws off the stock, again when he wakes up from his nightmare and for the third time just before shooting the Terminator at the night club. Not a single time is a shell ejected from the extraction port, which suggests Reese unloaded it prior to sawing off the stock, and only loaded it before he entered the night club.
Ithaca 37
Following the skirmish at the Tech Noir nightclub, the Terminator acquires his own Ithaca 37 with a full stock, and shortened magazine from the police car he hijacks after he is knocked in the middle of the street by Kyle and Sarah's car. He keeps it with him while he stalks Kyle and Sarah in the multi-story Car Park. He then uses it to exchange fire with Kyle in the ensuing chase. During the police station massacre, a few cops can be seen with Ithaca 37s.
M16A1
During the raid on the police station by the Terminator, several police officers head to the armory and begin passing out M16A1 rifles with 20-round magazines. Lt. Edward Traxler (Paul Winfield) is seen with an M16A1 and uses the rifle shoot the Terminator in the back (which resulted in the Terminator turning around and shooting Traxler with his own AR-18 rifle). Detective Hal Vukovich (Lance Henriksen) opens up on the Terminator with one after finding Traxler wounded by the cyborg. The Terminator returns fire with both the AR-18 and SPAS-12 killing him.
Ruger Security Six
In a deleted scene, a dying Lt. Traxler (Paul Winfield) gives Kyle Reese (Michael Biehn) a snubnose Ruger Security Six as he and Sarah Connor (Linda Hamilton) escape the police station. In another deleted scene, Kyle instinctively aims this revolver at Sarah when the two get into a tense confrontation. Later, at the Tiki motel, Kyle gives it to Sarah when he leaves to buy supplies. At the end of the film, Sarah carries a full size stainless Ruger Security Six on her lap as she rides through the Mexican desert.
Pipe Bomb
While at the motel, Kyle Reese and Sarah Connor can be seen assembling pipe bombs from components Reese purchased during a shopping trip. These bombs are then later used during the final car chase of the film with Reese throwing pipe bombs out the window of the commandeered pickup, trying to hit the Terminator pursuing them on a motorcycle, though he fails to score a hit. One pipe bomb is later used to blow up the tanker truck the Terminator hijacks, and the last one is used to blow off the Terminator's lower body, fragments from the blast killing an already-wounded Reese and injuring Sarah Connor.
Heckler & Koch G3A3
A number of Heckler & Koch G3 rifles can be seen in the hands of human Resistance fighters responsible for guarding a human bunker in 2029. The G3's civilian cousin, the HK91 rifle can be seen on the gun racks at the Alamo Gun Store in 1984.
Valmet M82A
A Valmet M82A is used as Kyle Reese's plasma gun in the future war scenes. This Valmet M82A moved the front sight to the body of the rifle rather than the barrel versus the M82. Interesting little trivia note: Kyle's appearance in these scenes was the inspiration for the cover art of the first Metal Gear game.
Browning M2HB Heavy Machine Gun
A Browning M2HB heavy machine gun is seen in the future war battle scene.
'General Dynamics RSB-80 plasma gun'
Pretty sure this was a M2HB .30cal with a custom shroud covering the barrel.
A machine gun that resembles a Maxim gun/British Vickers is used by the Infiltrator Terminator (Franco Columbu) in the Future war scene while raiding the Human's Underground Bunker as a rapid fire laser cannon. It is also seen on the sunroof of the car being chased by the Aerial HK.
Lahti L-39
Amongst other miscellanous weapons in the Alamo Gun Store, a WW2 Finnish made Lahti L-39 anti-tank rifle is on display.