In "Raising Caine" (S06E13), a Beretta 92FS is found in Julia Winston's car. It turns out to have been used by Rob Mason (Michael Muhney) to kill Bill Winston.
In "All In" (S06E16), one of the Mala Noche members is seen with a Beretta 92FS when they confront Horatio.
In "Down to the Wire" (S6E20), Frank finds a Beretta 92FS in Peter Cullen's (Chris Williams) office that he used to murder Debbie Schiffer. Calleigh is later seen with it when test firing it.
At the end of "Ambush" (S06E15), Chief Braga gives Horatio (David Caruso) a Browning Hi-Power with which to defend himself against the Mala Noche. In the following episode, "All In" (S06E16), Horatio is seen using the Browning to take out multiple members of the Mala Noche.
In "Dangerous Son" (S06E01), Detective Jake Berkeley (Johnny Whitworth) is seen with his Glock 17. An MDPD SWAT officer is also seen with a Glock 17 fitted with a tactical light.
In "Permanent Vacation" (S06E08), Vasco Torres (Jesse Garcia) draws a Glock 17 from his waistband when Eric is attempting to arrest him.
In "Going Ballistic" (S06E21), a fraudulent ammo manufacturer named Brad Gower (Steve Braun) uses a Glock 17 converted to full-auto fire with a 33-round high-capacity magazine. The gun is used to shoot his victim Manny Ortega (Jay Tavare) when he thought he had survived a fall from a high-rise window, killing a Medical Examiner that was caught in the line of fire.
In Season 6, Natalia Boa Vista (Eva La Rue) makes the transition to a full CSI and thus starts to carry a Glock 26. In the early episodes of the season she is seen training with it and other weapons.
In "Inside Out" (S06E03), Wolf finds an M1911 that was used at the scene of the bus accident.
In "Tunnel Vision" (S06E18), Dan Kirkland tries to pull an M1911 on Natalia. The gun is identified as a "Colt .45".
In "Going Ballistic" (S06E21), an M1911 is used by Colin Madison (Lyriq Bent) to kill Brad Gower. The gun is loaded with a special type of armor-piercing ammo (called "fused alloy") which is stated as being able to harden when sensing armor and shatter in flesh.
Det. Frank Tripp (Rex Linn) carries a SIG-Sauer P226 throughout season 6.
In "Tunnel Vision" (S06E18), Wolf finds a P226 that Charles Brighton (John Schneider) used to kill his accomplice then tried to bury in concrete.
Lt. Horatio Caine (David Caruso) continues to use his SIG-Sauer P229 during season 6.
In "Inside Out" (S06E03), Natalia Boa Vista (Eva La Rue) is seen using a SIG-Sauer P229 to train at the firing range.
In "Stand Your Ground" (S06E09), a carjack aims a pistol at Calleigh when he attempts to carjack her. The pistol is later identified by Calleigh as a "Smith & Wesson 459 with a wood grain grip and adjustable rear sight."
In "Going Ballistic" (S06E21), Horatio's son Kyle Harmon (Evan Ellingson) is seen with a Smith & Wesson 5906 which he clears and then reloads before placing it back in his bag. This is the same gun that he is seen with at the start of Season 7.
In "You May Now Kill the Bride" (S06E14), Greg Tanner's bodyguard is found to be carrying an Colt DS II (SF-VI) revolver which Calleigh is later seen firing it. The bodyguard is also seen firing the revolver in the nightclub to stop the patrons from grabbing money being thrown to the dancers.
In "All In" (S06E16), one of Calleigh's kidnappers is seen with a Smith & Wesson Model 15 Snub. Calleigh (Emily Procter) later picks up the kidnappers revolver and aims it at him.
In "Dangerous Son" (S06E01), at least one MDPD SWAT officer is seen with a Colt Model 933 (M4 Commando) rifle with EOTech holo-sight and a back-up rear sight.
In "Dangerous Son" (S06E01), at least one MDPD SWAT officer is seen with a Colt M4A1 rifle with EOTech holo-sight, weapon-light foregrip, RIS handguard fitted with black rail covers.
In "Down to the Wire" (S06E20), one of the SWAT officers responding to a fake call is seen with an M4A1.
In "Down to the Wire" (S06E20), one of the SWAT officers responding to a fake call is seen with a 10" barreled Heckler & Koch HK416 equipped with an ACOG, underbarrel light and standard LE stock.
In "Guerillas in the Mist" (S06E11), a crate full of of M16s (Not sure if they are M16s or M16A1s, M16A2s...) is seen covered in blood after the DX4 kills two of the gun runners.
In "To Kill a Predator" (S06E17), Deborah Radley (Stephanie Niznik) uses an unknown sniper rifle to kill a pedophile. (I don't think this gun is going to be identifiable. If an ADMIN agrees, please remove this statement.)
In "Guerrillas in the Mist" (S06E11), a fictional weapon known as the DX4 Vaporizer is used. It earns the nickname Vaporizer because it is able to literally turn a human being into a fine mist of blood. Near the end of the episode, Horatio arrives on a Miami airfield intending to intercept the weapon while it is being sold by a corrupt PMC CEO, Darren Butler (Sasha Roiz). Said CEO sees him coming and turns the DX4 on Caine's Hummer, destroying it with two bursts. Calleigh describes the weapon by saying "It's an electronic gun. It has over 200 individually fired barrels. When the trigger is pulled, an electronic current hits a primer on the back of each (caseless) round. Because there are no moving parts,there's nothing to slow it down. It's capable of firing a hundred thousand rounds per minute."
