In "Son of Mann" (S03E08), Liam Sykes (David Chisum) is seen with a Beretta Inox Non-Gun. In "A Priest Walks Into a Bar" (S03E13), a gunman fires at Mary and Marshal with a Non-Gun Beretta.
In "Father Goes West" (S03E01), TJ reaches for a Smith & Wesson 5906 in his truck before being stopped by Jimmy. In "A Priest Walks Into a Bar" (S03E13), during the shootout at the bus station, one of the shooters is using a Smith & Wesson 5906 with adjustable sights. It isn't clearly visible until he drops the gun after being shot.
Unknown 1911
In "Father Goes West" (S03E01), a gunman holds Jimmy's son hostage with an unknown 1911.
Unknown Pistol 2
In "Death Becomes Her" (S03E09), a mobster reaches for an unknown gun (possibly a SIG) in his glove-box.
In "Father Goes West" (S03E01), Jimmy McCabe (Donnie Wahlberg) breaks into a gun store and steals a Smith & Wesson Model 64. He later uses the gun to threaten the guy who beat up his son.
Unknown Revolver 3
In "No Clemency for Old Men" (S03E06), a bank robber is seen firing an unknown revolver.
Shotguns
Mossberg 500
In "Son of Mann" (S03E08), Mary is seen with a Mossberg 500 when storming the house of a suspect.
Unknown Shotgun
In "Witsec Stepmother" (S03E12), a jewelry store robber is seen with an unknown shotgun.
Rifle
M4A1
In "Her Days Are Numbered" (S03E10), an FBI agent is seen carrying an M4A1 when executing a search.
Collection
In "Coma Chameleon" (S03E03), a gun runner is seen with a collection of guns.