Deputy U.S. Marshal Marshall Mann (Frederick Weller) carries the full sized Glock 22 as his standard sidearm. His chief, US Marshal Stan MacQueen (Paul Ben-Victor), uses a G22 too.
Deputy U.S. Marshal Mary Shannon (Mary McCormack) has as her main carry weapon the Glock 23, which is the standard U.S. Marshal issue (as well as for the FBI and other agencies). In Season 1, Episode 2 (Hoosier Daddy), Shannon explicitly identifies her sidearm as a 'Glock 23'.
Mary's backup is the Glock 27 .40 which she has in an ankle holster. In Season 1, Episode 2 (Hoosier Daddy), she describes this explicitly as her "Glock 27" (as well as showing off her primary sidearm, her Glock 23). She uses this weapon when Spanky kidnaps her and no one sees the hidden weapon.
In "Hoosier Daddy" (S01E02), Luis Cruz (Steven Michael Quezada) pulls out a Stainless Taurus PT100 AFS pistol with gold accents during a drug negotiation gone bad.
In "Pilot" (S01E01), Frankie Santoro (Al Sapienza) uses a suppressed Smith & Wesson 910S. There is a continuity break in that the one he later carries in the room is a older Model 5906.
Frankie Santoro's (Al Sapienza) suppressed auto becomes a Smith & Wesson 5906 with old style fixed rear sights in the "Pilot" episode. In Season 1's "Trojan Horst" several assassins use 5906s with Novak sights.
Error creating thumbnail: File missingWalther PPK/S stainless - .380 ACPError creating thumbnail: File missingRichie Mastro'd head is slammed down on his hotel bed by Mary Shannon while Marshall Mann discovers Mastro's hidden firearm and dangles the Walther PPK/S with faux ivory grips in front of him. "Is this yours?". (S01E01)
Jericho 941 R
In "Trojan Horst" (S01E04), the assassin disguised as the 'wife' (D'Nette Pennington) uses a stainless Jericho 941 R Pistol.
In "Hoosier Daddy" (S01E02), a Mexican Drug Cartel sniper uses a Remington 700PSS to try to assassinate a witness. The giveaway is the barrel tip and the bolt handle shape, which both indicate the Remington 700 Action, though one cannot determine the exact caliber (either .308 Win or .300 Win Mag) from a front view (the action length must be visible).