During the roll call in the pilot episode, "Hill Street Station" (1.01), an undercover detective can be seen placing a Beretta M1934 during Sgt. Esterhaus's weapons inspection due to "alleged carrying of bizarre and unauthorized weapons by the officers of this precinct".
Mossberg 500
LaRue's partner, Sgt. Neil Washington (Taurean Blacque), places a pistol-gripped Mossberg 500 on the table during the pilot episode's weapons inspection. This appears to be the same shotgun seen later in the episode as used by Hector Ruiz (Panchito Gomez), one of the convenience store robbers.
Colt Mk IV Series 70
Det. John "J.D." LaRue (Kiel Martin) places a Colt Mk IV Series 70 on the table during the pilot episode's weapons inspection.
unidentified pistol
A female officer receives "assistance" from LaRue in removing a compact pistol from her leg holster during the pilot episode's weapons inspection.
Colt Detective Special (1st Generation)
Capt. Frank Furillo (Daniel J. Travanti) carries a first generation Colt Detective Special in a shoulder holster, notably seen when he removes the holster upon confronting Hector in the pilot episode. Det. J.D. LaRue (Kiel Martin) has a 1st Generation DS as his standard issue sidearm, seen when surrendering it with his badge (and having it returned to him). Det. Henry Goldblume (Joe Spano) reluctantly draws his Detective Special when he is cornered by thugs after his car blows a flat tire while driving through the ghetto in "Double Jeopardy" (1.05). He tells his supervisor that, until Capt. Furillo noticed, he had always carried the revolver unloaded, never expecting to use it.
Remington 870
Several officers from the Hill Street Station use Remington 870 shotguns. In the pilot episode, both Officers Bobby Hill (Michael Warren) and Andy Renko (Charles Haid) handle one during the armed robbery standoff with Hector in the pilot episode.
M16A1
The Emergency Action Team (EAT) utilizes M16A1 rifles.
Based on the muzzle breaks on some of the guns, they could be carrying MGC-M16 props, which are good stand ins when no one is firing. - Gunmaster45
Colt Python
Some of the Hill Street precinct officers carry Colt Python revolvers. The junkie who shoots Bobby and Renko in the pilot episode fires four shots from a 6" barrel Python, later recovered by LaRue and Washington while chasing down Billie (Karole Salmon) in "Film at Eleven" (1.06).
Smith & Wesson Model 28
Many of the officers carry Smith & Wesson Model 28 revolvers, including Bobby Hill (Michael Warren), undercover Det. Sgt. Michael "Mick" Belker (Bruce Weitz), and others. Hector's friend Juan (Jay Moreno) in the pilot episode also holds a Model 28 on the hostages.
Officer Fuentes (Steven Bauer) carries a Smith & Wesson Model 19 in "Presidential Fever" (1.02), until it is taken from him by a mob of angry Puerto Ricans when he and Officer Harris wrongly accuse them of burglary. Bobby Hill (Michael Warren) keeps one in his purse when he goes undercover in drag to catch a serial rapist in "Double Jeopardy" (1.05).
Smith & Wesson Model 29
EAT commander Sgt./Lt. Howard Hunter (James B. Sikking) keeps a Smith & Wesson Model 29 in a large shoulder holster. It is first scene in "Politics as Usual" (1.03), when Hunter is telling Capt. Furillo that "a Steyr SSG hits from a thousand yards" during an argument about security for the President's upcoming visit to Hill Street Precinct.
Undercover Det. J.D. LaRue (Kiel Martin) carries a third-generation Colt Detective Special in an ankle holster in "Politics as Usual" (1.03) when he tells his partner, Sgt. Washington, that he's got "a .38 strapped to [his] ankle". Det. Washington (Taurean Blacque) also carries a 3rd Generation Detective Special, notably seen when arresting Eddie Hoban (Rob Berger) in "Film at Eleven" (1.06). Capt. Frank Furillo (Daniel J. Travanti) draws his own from a shoulder holster when questioning Eddie's girlfriend Sherry in "Choice Cut" (1.07), trying to see if she was telling the truth by discerning between his own Detective Special and a suspect's Colt Python.
Ithaca 37
Several officers at the Hill Street station, including Sgt. Esterhaus (Michael Conrad) prepare for a potential attack from the local gangs in "Can World War III Be An Attitude" (1.04) with Ithaca 37 shotguns. Bobby Hill (Michael Warren) grabs one from his and Renko's patrol car en route the armed robbery in "Choice Cut" (1.07).