Vincent (Tom Cruise) carries a Heckler & Koch USP in .45 ACP which we see him draw and fire several times. Of particular note for this film is that Cruise, as Vincent, fires the first five rounds of his "briefcase" scene attack with deliberate aim against two targets in less than one and a half seconds. This results in obvious physical, but also dramatic and cinematic, impact as it demonstrates that Vincent's degree of skill and focus is clearly on a different level than that of the armed street thugs he encounters.
Cruise trained on a LA County Sheriff's Department range in combat scenarios with a former SAS (British Special Air Service) operator, with live ammunition to increase his competency with a pistol, according to Michael Mann's DVD commentary. Cruise did not have live ammunition experience with a pistol prior to shooting "Collateral". Mann also specifically says in the DVD commentary that Vincent's USP is the .45 ACP model. It is also namechecked in the script as an "HK .45".
Ruger Mk II Pistol
Vincent (Tom Cruise) assassinates Daniel (Barry Shabaka Henley) with a suppressed Ruger Mk II Pistol chambered for .22 LR. He catches his head before it smashes on the table, but in reality the suppressed shots would be louder than the slam anyway, though this is possibly to keep the blood from splashing over the table, so the ruse that Daniel is just sleeping will last longer.
(An interesting note: Named in the script as a .22 Ruger with a thick, silent barrel.)
Smith & Wesson 3913
Detective Fanning (Mark Ruffalo) draws a Smith & Wesson 3913 in 9mm when he goes to Ramon's apartment to find him and sees the door has been left open. (In the script, this was named as a Beretta.)
Smith & Wesson 5906
Vincent lifts a Smith & Wesson 5906 from the desk guard he kills at the Federal building and uses it as he hunts down his final target, Annie (Jada Pinkett Smith). (In the script, Vincent would have had this gun as a back-up, and it was to be a Para-Ordnance .45.)
SIG-Sauer P232
One of the robbers pulls a SIG-Sauer P232 on Max when he calls for help when tied up in the cab. He points it at Vincent when he confronts them for his briefcase before being killed. (In the script, this was simply named as a "Chrome .380".)
Jericho 941
A two-tone Jericho 941 ("Baby Eagle") can be seen in the hands of a bodyguard in Club Fever. He fires it into the air after mistaking an FBI agent for an assassin.
Sphinx AT 2000
During the Club Fever shootout, a guard tries to draw a Sphinx AT 2000.
Glock 22
We briefly see an FBI agent entering Club Fever with his FBI issue Glock 22 at the ready. When a bodyguard notices the agent with his gun drawn he mistakes him for an assailant and draws and fires his own pistol. (The identity of this weapon as a Glock 22 has been confirmed by an armorer who worked on the film.)
Glock 17L
One of the hitmen hired by Felix is seen armed with a long slide Glock 17L fitted with a laser pointer and tries to shoot Max (Jamie Foxx) with it in Club Fever before being killed by Vincent (Tom Cruise).
M1911A1
One of Felix's guards can be seen ready to draw his M1911A1 on Max as he tries to get a spare zip drive for Vincent. In Club Fever when this guard is sent to kill Max, he tries to fire his M1911A1 at him before Vincent fires on him instead.
Ruger KP89
A bodyguard draws and fires a Ruger KP89 at the FBI special agents entering Club Fever.
Beretta 92FS
An LAPD officer (who is an actual officer, not an actor) draws his issued Beretta 92FS on Max (Jamie Foxx) after finding the body of Vincent's (Tom Cruise) first victim, Ramone, in the trunk of the crashed cab.
SIG-Sauer P226
Immediately proceeding the shootout at Club Fever, Lead FBI agent Pederosa (Bruce McGill) is seen holding a SIG-Sauer pistol which is most likely a SIG-Sauer P226.
Machine Pistols And Submachine guns
Steyr SPP
A Steyr SPP is seen in the hands of a bodyguard at Club Fever. The Steyr Special Purpose Pistol is the civilian version of the Steyr TMP. The major concessions the civilian model makes are the removal of the fore grip and the lack of full-auto firing capability which is rather evident since he is only seen firing it semi-auto (the full-auto bursts are heard off screen). Vincent was originally supposed to use one of these to take out a guard before using his USP.
Colt RO635 9mm
A Colt 9mm Submachine Gun (RO635) fitted with a Surefire M500AB forend weaponlight is used by one of the FBI Agents who goes to Club Fever. In the script these were generically referred to as "CAR-15s."
One of the bodyguards in Club Fever is armed with a Sawed Off Over and Under Shotgun but is shot by Vincent before he can use it and fires a shot into the air as he dies.