Several LAPD officers and detectives carry the Beretta 92FS as their sidearm, including Detective Sammy Bryant (Shawn Hatosy), Detective Daniel "Sal" Salinger (Michael McGrady), Detective Nate Moretta (Kevin Alejandro), Officer Bill "Dewey" Dudek (C. Thomas Howell), Detective Russell Clarke (Tom Everett Scott), and a number of other officers. This weapon is on the LAPD approved carry list. Also used by at least one of the sheriff's deputies in "Salley in the Alley" (S1E04). This weapon is also on the Sheriff's Department approved carry list.
Taurus PT99
Two gang members use Taurus PT99 pistols in "Derailed" (S1E07).
Smith & Wesson 5906
Officer John Cooper (Michael Cudlitz) carries a Smith & Wesson 5906 (as evidenced by its double stack frame) as his duty sidearm. This weapon is on the LAPD approved carry list.
Glock 22
Officer Ben Sherman (Ben McKenzie) carries a Glock 22 as his sidearm. This weapon is standard issue to all LAPD probationary officers. Upon completion of probation, they may choose to switch to another weapon on the approved carry list, or they can stay with the Glock. Officer Chickie Brown (Arija Bareikis) also uses a Glock 22 as her sidearm, although her weapon is fitted with a Surefire X-300 tactical light. Detective Ray Suarez (Clifton Collins, Jr.) can also be seen using a Glock 22 in episode 11.
Heckler & Koch USP
One of the Sheriff's deputies is seen carrying a Heckler & Koch USP in "Sally in the Alley" (S1E04). The correct model would be the .45 ACP version, as that is the only USP on the Sheriff's Department approved carry list. A gang member uses a two tone USP to shoot a non-gang affiliated black kid in the pilot "Unknown Trouble" (S1E01).
Smith & Wesson Model 60
In the pilot episode "Unknown Trouble" (S1E01), a Hispanic gang member uses a Smith & Wesson Model 60 in a shooting. The same gang member uses it to shoot Dewey later on in the episode.
Jericho 941
A third gang member uses a Jericho 941 in the shooting in the pilot episode "Unknown Trouble" (S1E01) .
Smith & Wesson 3913
Detective Adams (Regina King) uses a Smith & Wesson 3913 as her duty gun. She gives it to the witness she is protecting in Season 1's "Derailed" (S1E07).
Raven Arms MP-25
A woman pulls what appears to be a Raven Arms MP-25 compact pistol on actor Timmy Davis (Tom Sizemore) in "See the Woman" (S1E03). One is also seen in the opening credits.
Desert Eagle (Non Gun)
Among Timmy Davis's other weapons is a Non Gun Desert Eagle in "See the Woman" (S1E03).
SIG Sauer P228
In the Season 1 finale "Derailed" (S1E07) one of Marta's bodyguards pulls a SIG Sauer P228 on Marquis. Later in the episode, one of the gangsters sent to Lydia's house uses a nickel P228. He fires a shot at Lydia, but misses and is subsequently killed. Another is briefly seen used by one Marta's men to execute a hitman at the beginning of the episode.
SWAT officers in "Two Gangs" (S1E05) carry what appear to be Kimber Custom TLE II pistols (the sidearm of all LAPD SWAT officers) in their holsters.
Unknown Handguns
Skylar's Compact Handgun
In "Mozambique" (S1E02), Skylar carries an unknown compact pistol which he fires at Chickie before dropping it in an alley.
The Shop Owner's Handgun
In "Mozambique" (S1E02), the owner of a convenience store holds an unknown pistol on a would-be robber. It appears to have a stainless or nickel finish with black grips.
Shotguns
Remington 870
Several LAPD officers are seen using Remington 870 shotguns, once seen equipped with tactical lights in the pilot episode "Unknown Trouble" (S1E01). They are often seen in the shotgun racks of the police cars and is the standard shotgun for the department. Detective Clarke notably uses one loaded with beanbag ammo in "Mozambique" (S1E02). Detective Adams (Regina King) also carries one during a raid in "Sally in the Alley" (S1E04).
Winchester Model 1300 "Defender"
Detective Adams keeps a Winchester Model 1300 "Defender" in a safe in her home. She uses it to shoot the gang members trying to kill a witness in her home in Season 1's "Derailed" (S01E07). It is identified as a Winchester by the magazine cap.
Benelli M1 Super 90
A SWAT officer is seen with a Benelli M1 Super 90 in Season 2's "What Makes Sammy Run?" (S2E05).
Assault Rifles
M4 Carbine
LAPD SWAT officers are armed with M4 Carbines during the raid on a gang member's arms dealing warehouse in "Two Gangs" (S01E05).
Timmy Davis uses a Non-Gun AK-47 in "See the Woman" (S1E03).
Submachine Guns
MAC-10
A gang member can be seen with a MAC-10 as he flees Detective Adams' house in "Derailed" (S1E07).
Machine Guns
M60E3
Officer Dudek (C. Thomas Howell) uses an M60E3 in Season 1's "See the Woman" (S1E03). When asked how he could own a class-3 firearm, Timmy Davis says the props guy converted it from a semi automatic to fully automatic.
FN MAG
An FN MAG (most likely a substitute for the M240 machine gun) is briefly seen during the raid on Big Wayne's residence in "Two Gangs" (S01E05).