Several LAPD officers and detectives carry the Beretta 92FS as their sidearm, including Officer Sammy Bryant (Shawn Hatosy), Officer Bill "Dewey" Dudek (C. Thomas Howell), and Officer Ferguson (Lou Diamond Phillips). This weapon is on the LAPD approved carry list.
Many officers in the series the .40 caliber Glock 22 (which is the standard-issue handgun for the LAPD) as their sidearm. Officer Ben Sherman (Ben McKenzie) continues to carry the Glock 22 as his sidearm from the last 3 seasons. Newly-introduced, Officer Jessica Tang (Lucy Liu) mentions that she carries the "Glock .40" as her sidearm and draws it in "Wednesday" (S4E01).
A pimp named Ronnie (Cle Shaheed Sloan) is seen firing on Sherman and Bryant with a Heckler & Koch USP, equipped with a stainless slide in "Risk" (S4E09).
Officer John Cooper (Michael Cudlitz) continues to carry the Smith & Wesson 5906 (as evidenced by its double stack frame) as his duty sidearm. This weapon is on the LAPD approved carry list.
Detective Lydia Adams (Regina King) continues to carry a Smith & Wesson 3913 as her on-duty sidearm. She is seen drawing it in "Risk" (S4E09). In "Wednesday" (S4E01), Officer Ben Sherman appears to carry a Smith & Wesson 3913 as his off duty weapon. He can be seen taking it out of his locker stowed in an IWB thumb break holster. He then fires it later in the episode when a shooter enters the LAPD station with a shotgun and opens fire.
The Remington 870 Police Riot Magnum is the standard shotgun used by the LAPD in the series. Officers are often seen carrying the shotgun (along with one carrying beanbag rounds) to their squad cars. In Season 4's premiere "Wednesday" (S4E01) Officer Ben Sherman is seen carrying the standard and Officer Sammy Bryant is seen with the "less-lethal" model loaded with beanbag rounds. In "Underwater" (S4E02), Captain Joel Rucker (Carl Lumbly) uses the Remington 870 to fire the less lethal beanbag round.
In Season 4's premiere "Wednesday" (S4E01), an active shooter is seen entering the station armed with a Remington 870 Wingmaster Shotgun fitted with an extended mag tube.
An LAPD officer armed with an M4A1 Carbine fitted with an EOTech sight is seen entering after the shootout in the police station in Season 4's premiere "Wednesday" (S4E01).