The Beretta 92FS is seen used by various characters in the series including police consultant Adrian Monk (Tony Shalhoub), Captain Stottlemeyer (Ted Levine), and Lt. Randy Disher (Jason Gray-Stanford). The Beretta is Randy's sidearm throughout the first half of the series, before he swaps to using a Glock 17 sometime prior to the seventh season.
In Season 3's "Mr. Monk Takes His Medicine" (S03E09), "Mr. Monk Gets Cabin Fever," (S03E12), Stottlemeyer carries a Beretta 92FS instead of his usual Smith & Wesson 3913. In "Cabin Fever," both he and Disher use Berettas during the shootout with two Chinese hitmen.
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"Lane & Westen"
Probably because of legal objections that came after the episode "Mr. Monk and the Very, Very Old Man," subsequent Beretta pistols which appeared in the series were given the fictional name "Lane & Westen." Even with the alternative name, they are clearly Beretta pistols, and in "Mr. Monk and the Captain's Wife," Evan Coker's handgun is explicitly referred to by Disher as a Beretta. To avoid confusion for any viewers, all "Lane & Westen" pistols will be referred to in this article by the "Beretta" name.
Glock 17
In Season 3's "Mr. Monk Gets Cabin Fever" (S03E12), FBI Special Agent Grooms (Josh Stamberg) shoots a Chinese assassin with a Glock
Springfield 1911 Loaded
In the Season 3 episode "Mr. Monk Takes His Medicine," (S03E09) Lester Highsmith (Ken Marino) uses what appears to be a Springfield 1911 Loaded to open fire on police officers.
Walther P38
In the episode "Mr. Monk Takes His Medicine" (S03E09) Monk uses a water pistol modeled on a Walther P38 in an attempt to bluff Lester Highsmith (Ken Marino) at an industrial park, only, to his embarrassment, to let the barrel drip, revealing its true nature. Monk's water pistol, noticeably, lacks several safety features that are necessary on water pistols to tell them apart from regular pistols (to avoid the risk of child injuries).
Walther PPK
Hal Tucker (Andy Richter) takes Monk hostage with a Walther PPK in "Mr. Monk Makes a Friend" (S05E11).
Walther PPK/S
In the Season 3 premiere "Mr. Monk Takes Manhattan" (S03E01), Steven Leight (Jeffrey Dean Morgan) shoots and kills his wife in Central Park with what appears to be a "Non Gun" version of the Walther PPK, then kills the Latvian ambassador and his bodyguards later on with the same weapon. Incongruously, the bullets recovered from the crime scene are described as .22 caliber (a pea shooter), when the Walther PPK is chambered in .32 ACP and .38 ACP.
Submachine Guns
Heckler & Koch MP5A2
The SWAT officers in "Mr. Monk and the Kid" (S03E16) use Heckler & Koch MP5A2 rifles during the raid on the Novaks' house.
Ingram MAC-10
In the Season Three episode "Mr. Monk Meets the Godfather" (S03E05) a crew of mafia hoods from the Lucarelli crime family are gunned down at a barber shop with one of their own MAC-10s.
Rifles and carbines
Blaser 93 Sniper Rifle
In "Mr. Monk Gets Cabin Fever," one of the Chinese hit men uses a Blaser 93 sniper rifle during the shootout at the Willowby cabin.
Norinco Type 56-1
In "Mr. Monk and the Election" (S03E15) illegal arms dealer Jack Whitman (Nick Offerman) tries to disrupt Natalie's campaign headquarters by shooting up the office with a Norinco Type 56-1. From Monk's statement, Stottlemeyer determines that they are looking for a rapidfire semiautomatic. It is later revealed that he was actually trying to shoot out a copier machine with an incriminating document containing his client's names and the weapons being sold to them.
Ruger Model 77
In Season 3's "Mr. Monk and the Employee of the Month" (S03E07), Monk grabs a Ruger Model 77 (identifiable from the paddle stock, and the built-in strap ring on the forestock, both of which are visible for a second) from the sporting goods section of the "Mega-Mart" and tosses it to his ex-partner, Joe Christie (Enrico Colantoni), who uses it to shoot out the tire of the getaway van.