Castle - Season 3
The following weapons were used in Season 3 of the television series Castle:
A Glock 26 is carried by Beckett as her backup. This pistol is seen used by Castle in order to defend himself in the Season 3 premiere "A Deadly Affair" (S3E01).
An M1911A1-type pistol is found to be the murder weapon in Season 3's premiere "A Deadly Affair" (S3E01).
Safari Arms Matchmaster 5
Jericho 941 R
Earl (Craig Gellis) is seen using a stainless Jericho 941 R to fire on Castle and company in "A Deadly Affair" (S3E01).
One of Hal Lockwood's men uses a Desert Eagle in an attempt to shoot out one of Ryan's kneecaps in "Knockdown" (S3E13).
Bond Arms Snake Slayer IV
Montgomery (Ruben Santiago-Hudson) uses a Bond Arms Snake Slayer IV Derringer as his holdout weapon during his confrontation with Lockwood in Season 3's finale "Knockout" (S3E24). It is the IV version of the Snake Slayer as noted by its longer barrel, and although normally chambered in .45 this pistol appears to use the .38/.357 barrel, as Montgomery loads it with the same rimmed rounds he uses in his revolver.
In "Punked" (S3E04), Daniel Goldstein and Adam Murphy are found to have each used flintlock pistols in a duel to impress a woman. Later, while trying to determine whether to charge Adam with murder or manslaughter, they hilariously succeed at hitting everything in the range but the targets. After several failed attempts, Castle uses duct tape to attach a scope, and laser sight in a last ditch attempt to hit the target. Other models are also seen being held by Ivan Podofski (Muse Watson) in photos on a antique firearms social networking page.
Jay Hixton (Skoti Collins) found dead, his Colt Python next to his body in "Lucky Stiff" (S3E14).
Smith & Wesson Model 10
A Smith & Wesson Model 10 is seen used at the beginning of "Knockdown" (S3E13).
Smith & Wesson Model 19
Smith & Wesson Model 60
In "Under the Gun" (S3E03), bail bondsman Deon Carver is seen brandishing his Model 60 when he returns to his office and notices somebody has broken in. Castle is seen holding a snubnose revolver as Beckett, Ryan & Esposito clear a murder victim's apartment.
In "Punked" (S3E04), Castle is seen wielding what appears to be a custom engraved replica of a Colt 1851 Navy revolver while bursting through his front door and catching his daughter snogging her boyfriend.
Irwin Finkelstein is seen holding what appears to be a Remington 1875 in pictures on a antique firearms social networking page.
Colt Single Action Army
In "Punked" (S3E04), another of Finkelstein's revolvers, a Colt Single Action Army is seen.
Heckler & Koch MP5K
Some of Lockwood's guards are armed with the Heckler & Koch MP5K in "Knockout" (S3E24).
Mossberg 500AT Shotgun
In "Under the Gun" (S3E03), Mike Royce (Jason Beghe) is seen wielding what appears to be a Mossberg 500AT shotgun during a confrontation between the detectives, Gayle Carver (Sophina Brown) and Clifford Stuckey (James Handy).
High Standard K-100 Shotgun
What appears to be a High Standard K-100 Shotgun is held by Clifford Stuckey (James Handy) during a confrontation with Det. Gayle Carver (Sophina Brown) and Det. Mike Royce (Jason Beghe) in "Under the Gun" (S3E03).
ROCK SOPMOD M14
In "Knockdown" (S3E13), Hal Lockwood (Max Martini) uses a suppressed ROCK SOPMOD M14 to shoot at John Raglan, and later during a shootout with Beckett. It appears to have a Harris bipod and AN/PEQ-2/5. It is supposedly chambered in .338, despite the round being much too large for fit the 7.62x51mm chamber.
In "The Final Nail" (S3E15), detectives arrive at the crime scene to find a female victim with multiple flat-head nails protruding from her skull. Behind a nearby chair they find a nail gun. It appears to be a cosmetically altered KitPro series judging by the shape of the butt, housing assembly (screws pointing aft), housing vents on the side and top, and the 'over/under' 'muzzle'. I think the 'over' is a nail depth gauge.