In "Battle Scars" (S06E05), a robber is seen with a Browning Hi-Power.
In "Uncertainty Rules" (S6E16), a Browning Hi-Power is seen being used by a thug and later picked up by James Roberts (Joe Reegan) and he holds it on Rufus Knox (Dominic Keating).
Two of the CSIs use 2nd Generation Glock 17 pistols throughout the series, notably Det. Mac Taylor (Gary Sinise) and Det. Danny Messer (Carmine Giovinazzo) carry Glock 17s. Chief Brigham Sinclair (Mykelti Williamson) is seen with one in a few episodes. Some of the uniformed NYPD Officers, as well as random crooks and other characters use Glock 17s as well. In recent episodes, 3rd Generation Glock 17s begin to make appearances. The Glock Model 19 is the only Glock pistol authorized for carry by the NYPD for its officers. This error is often made by television shows and movies.
In "Cuckoo's Nest" (S6E08) and "Manhattanhenge" (S6E09) , a serial killer named Hollis Eckhart (Skeet Ulrich) uses a Smith & Wesson 3913 "Ladysmith" as his weapon of choice, using it in "Cuckoo's Nest" to kill one of his victims that attempts to escape, and later uses it twice in "Manhattanhenge", using it to pistol whip a store owner and later uses it in a standoff with Det. Taylor and Det. Flack, threatening to shoot himself with it, but drops it at the pleads of Det. Taylor and his own vision of his late wife, Calliope (Josie Davis).
In "Blacklist (Featuring Grave Digger)" (S06E02), Junior Mosley (Evan Jones) is seen pulling a gun out of his waistband when he tries to carjack Aaron Dexter.
In "Uncertainty Rules" (S6E16), Rufus Knox uses a Colt Python, firing it at Det. Taylor and James Roberts, but never scores a hit and runs out of ammo.
In "Unusual Suspects" (S6E21), Colt Python is carried by a bank robber and is identified as a ".357" by Det. Bonasera.
In "Cuckoo's Nest" (S06E08), Flack is seen using the Smith & Wesson Model 340PD as his back up weapon. Terrence Davis (Nelly) picks the gun up just in time to save Flack from being stabbed.
In "Blacklist (Featuring Grave Digger)" (S06E02), ESU officers are seen carrying Heckler & Koch MP5A2s.
In "Means to an End" (S06E09), ESU officers are seen with Heckler & Koch MP5A2s while searching for Hollis Eckhart (Skeet Ulrich).
In "Epilogue" (S06E01), a gang of extortionists use a Steyr SPP converted to fire full-auto to shoot up several crowded areas, including a bar in which the CSI Team was in, killing only a bartender and wounding Det. Messer. It is even identified as a Steyr SPP by Det. Taylor, commenting on how it wasn't very accurate.
In "Cuckoo's Nest" (S6E08), during a flashback a deranged man is seen using a Mossberg 500 kill his girlfriend, and then uses it to shoot up the other employees at the City Surveyor's Office, including the wife of serial killer Hollis Eckhardt (Skeet Ulrich), Calliope (Josie Davis) wounding Eckhardt in the face with it in the process.
In the CSI crossover episode "Hammer Down" (S06E07), Dr. Ray Langston (Laurence Fishburne) uses a Remington 870, although in a continuity error this changes to a Mossberg 590. Multiple Remington 870s can also be seen sitting in the ESU truck.
In "Vacation Getaway" (S6E23), Detective Flack can be seen with a Remington 870 shotgun.
