The Glock 17 is a handgun used throughout the series. In "Two of a Kind" (S2E08), the crossover episode with the series Crossing Jordan, Det. Woody Hoyt (Jerry O'Connell) is armed with the Glock 17. The gunman who shot Ed Deline uses a Glock 17 in "Father of the Bride" (S3E23) and is seen with the pistol in "Father of the Bride Redux" (S4E01). FBI agents are armed with the Glock in "3 Babes, 100 Guns and a Fat Chick" (S5E13).
SIG-Sauer P232
Ed Deline (James Caan) can be seen wielding a stainless SIG-Sauer P232 in .380 ACP, most notably to shoot the father of Mary (Nikki Cox), in "Heroes" (S4E17). Dual SIG-Sauer P232 pistols are seen used in "3 Babes, 100 Guns and a Fat Chick" (S5E13).
SIG-Sauer P226
A henchman appears to use a SIG-Sauer P226 in "Delinda's Box, Part 2" (S4E06).
SIG-Sauer P228
The SIG-Sauer P228 is the pistol used by some of the security guards of the Montecito. Danny uses one taken from a guard in "Father of the Bride Redux" (S4E01).
Colt Detective Special
Mary Connell (Nikki Cox) uses a nickel Colt Detective Special to aim at her father toward the end of "Heroes" (S4E17). She is seen purchasing it from a pawn shop in a previous episode, "Bare Chested in the Park" (S4E15), referring to it as a ".38".
Smith & Wesson SW1911SC (Gunsite Edition)
A.J. Cooper (Tom Selleck) carries the Gunsite Edition of the Smith & Wesson SW1911SC with stag grips, notably in "3 Babes, 100 Guns and a Fat Chick" (S5E13). A similar pistol was the weapon of choice for Selleck in his Jesse Stone film series.
Walther PPK/S
In "Two of a Kind" (S2E08), Madeline Pillsbury (Valerie Cruz) uses the Walther. This pistol is used by Danny McCoy (Josh Duhamel) later in the episode. A nickel Walther PPK/S can be seen in Ed Deline's safe deposit box in London in "Father of the Bride Redux" (S4E01).
Walther "Non Gun"
When Ed is seen using a pistol to "shoot" Kareem Sharif in "Died in Plain Sight" (S4E02), this weapon resembles a Walther Non Gun.
Walther P38
A dealer is armed with a Walther P38 in "Died in Plain Sight" (S4E02).
Submachine Guns
Heckler & Koch MP5A2
The Heckler & Koch MP5A2 is carried by SWAT officers while making a raid in Las Vegas in "Father of the Bride Redux" (S4E01).
Rifles/Carbines
Colt M4A1
In "Have You Ever Seen the Rain?" (S2E01), Danny McCoy (Josh Duhamel) is seen in his hotel room with his M4A1 after returning from Iraq in season 2. Although, there is no way he could get the weapon he used in Iraq. Danny uses the M4A1 in the final gun battle in "Delinda's Box, Part 2" (S4E06).
Ruger Mini-14
In "Have You Ever Seen the Rain?" (S2E01), two men are seen using Ruger Mini-14 rifles to shoot at bottles.
Shotguns
Remington 870 Police
A Remington 870 Police model is carried by SWAT officers while making a raid in Las Vegas in "Father of the Bride Redux" (S4E01).
Mossberg 590 Mariner
A Mossberg 590 Mariner shotgun with a pistol grip and high-capacity magazine tube is used in "3 Babes, 100 Guns and a Fat Chick" (S5E13).
Other
"100 Guns"
Several submachine guns, machine guns, shotguns and pistols are seen on a hotel bed in "3 Babes, 100 Guns and a Fat Chick" (S5E13).