Modified Benelli M2 Super 90 Shotgun with black synthetic fore end, tactical pistol grip stock, extended magazine tube and capable of taking box or drum magazines used by the "Slag" robbers at the beginning of the movie.
Ruger AC556
The 2nd Slag gunman at the beginning of the film discards his Remington 870 short shotgun and uses a Ruger AC556 with an aftermarket synthetic pistol grip stock. Later he throws down the AC556 from his perch on a L.A. Billboard. It is replaced with a rubber casting of the weapon at this point.
Micro Uzi
Carried by the human henchman during the first robbery heist, in reality an execution.
Beretta 92FS
Matthew Sykes (James Caan) at the beginning of the film uses a Beretta Model 92FS.
Smith & Wesson 5906
Det. Bill Tuggle (Roger Aaron Brown) carries a S&W 5906 pistol at the beginning of the film.
Freedom Arms .454 Casull Revolver
Upset over the death of his human partner, Det. Sgt. Matthew Sykes (James Caan) trades out his Beretta 92FS and picks up a Freedom Arms .454 Casull Revolver.
Remington 870 Shotgun
A full sized Remington 870 police shotgun is used by Det. George Francisco (Mandy Patinkin) when he is pursuing the mutated slag monster. Also a short barreled Remington 870 with a synthetic black pistol grip (with no stock) is used by the 2nd Newcomer robber at the beginning of the film.
Commercial M1911A1
Carried by Rudyard Kipling (Kevyn Major Howard), better known as Rafterman in the film Full Metal Jacket. Kevyn retired from acting in 1999 and is a successful (and talented) photographer working in Los Angeles.
Unknown S&W Revolver
Not sure what this is. I have some ideas, but the fact that this film was made in 1987 (released in 1988) eliminates some of my suggestions. Thoughts anyone?
My best guess would be a Smith & Wesson 586. - Gunmaster45
Smith & Wesson Model 10
A female police officer at the Police Target range is seen using a standard Smith & Wesson Model 10. It is not unrealistic for a woman officer to choose a smaller caliber round than her male counterparts.
Smith & Wesson Model 27
Smith & Wesson Model 28
Unknown Snub Nose Revolver
Detective Francisco (Mandy Patinkin) pulls out his backup revolver, but it is too dark to determine what it is.