A nickel plated Smith & Wesson Model 36 with Pachmayr grips is a personal sidearm of police Commissioner Lydie Herzog (Sophie von Kessel). During the shootout with Norbert Loggia's bodyguards her revolver switches to a Ruger SP101 (see below) and then back to S&W.
Ruger SP101
During the shootout with Norbert Loggia's bodyguards Commissioner Lydie Herzog (Sophie von Kessel) uses a Ruger SP101 that switches back to her usual nickel plated Smith & Wesson Model 36 after the shootout.
Numerous police personnel carry revolvers in holsters. Some revolvers are also seen in action but they aren't seen clear enough for identification (though Manurhin F1 or MR-73 are most possible versions).
Pistols
Colt M1911
When Frank Riva (Alain Delon) comes back in Paris, his old friend Xavier Unger (Jacques Perrin), now the director-general of the General Directorate of the National Police, hands back Riva's Colt M1911 that was kept by Unger for a quarter century. Riva uses this pistol throughout the season.
Drug boss Maxime Loggia (Luis Marquès) uses a Smith & Wesson 6906 when he takes as hostage pregnant Nina Rizzi (Mélanie Maudran), Frank Riva's daughter. A female enforcer of Colombian drug mafia Minda Fierro (Carmela Ramos) uses same looking pistol, most likely same prop.
M1911-style pistol
A stainless steel (or possibly but less credible nickel plated) M911-style pistol is used by Marie Forlo (Alice Taglioni) during her revenge on aged and retired criminals who killed Marie's father many years ago. The pistol has uncommon combination of classic 1911-style slide with vertical serration and angular trigger guard.
Another M1911-style pistol is seen in hands of Loggia's bodyguard (this character, armed with a Taurus PT908 (see below) was gunned by Commissioner Herzog but then he appears again, this time holding the M1911-style pistol). This pistol also has vertical slide serration and angular trigger guard, but differs in finish (blued) and has adjustable rear sight.
One more M1911-style pistol is used by the enforcer of Colombian drug mafia Jimmy Esperanza aka Jefferson Villa (Eric Defosse).
Taurus PT908
During the killing of aged criminals Marie Forlo's (Alice Taglioni) gun switches from M1911-style pistol to a stainless Taurus PT908. Marie continues using this pistol until she is disarmed by a Loggia's bodyguard.
Beretta 92 style
A pistol, used for assassination of Commissioner Tony Rezzoni, is hidden by Jean-Luc Roth and later found by Frank Riva. Riva threatens Roth with this pistol. This is Beretta 92 style pistol but as the back of the slide together with the grip and trigger guard is wrapped in some soft cloth, it's impossible to identify the gun as Beretta, a Taurus PT92 or some other Beretta clone.
A SIG-Sauer P220 style pistol, fitted with weaponlight, is used by an officer of special police unit during the attack on drug dealer Eric Chaelle's hideout. Some holstered pistols, seen in this scene, may be of same model.
Various pistols
Various pistols that are seen partially or in distance appear in the series.
Non-Gun Beretta 92F
In the opening scene corrupt police Lt. Jean-Luc Roth (Matthieu Rozé) murders Commissioner Tony Rezzoni (Philippe Baronnet), shooting him in the back. In this scene Roth's pistol appears to be a Non-Gun Beretta 92F.
Mockup pistols
In several scenes real guns are substituted with mockups.
Submachine Guns
Mini Uzi
In the opening scene Commissioner Marc-Antoine "Tony" Rezzoni (Philippe Baronnet) and Lt. Jean-Luc Roth (Matthieu Rozé) use Mini Uzi submachine guns, fitted with tactical flashlights, mounted on the receivers. One of Norbert Loggia's bodyguards is armed with a Mini Uzi during the shootout with police.
Beretta M12
Beretta M12 submachine guns are used by police personnel in several scenes.
Heckler & Koch MP5A3/MP5F
Heckler & Koch MP5A3 submachine guns are seen in hands of police personnel in several scenes. Some of them, if not all, appear to be French police issued version MP5F.
Assault Rifles
SIG SG 552
Several police officers carry SIG SG 552 compact assault rifles during the storming of the hideout of drug dealer Eric Chaelle.
Sniper Rifles
SIG SG 550 SR
A SIG SG 550 SR sniper rifle (probably a single prop reused) is seen in hands of a police sniper and of a drug mafia hitman, hunting for Marie Forlo.
Bolt action sniper rifle
A bolt action sniper rifle of unidentified model is used by Maxime Loggia's lieutenant Renaud Berson (Jean-Claude Dauphin).
Shotguns
Remington 870
In the opening scene Capt. Hervé Sebastian (Cédric Chevalme) and Lt. Guy "Guido" Buscema (François Vincentelli) are armed with Remington 870 shotguns with pistol grips. Buscema's shotgun is fitted with Choate folding stock, Sebastian's shotgun has a rail system and raised vented rib, and both guns are fitted with underbarrel flashlights. A Remington 870 with Choate folding stock is also used by an officer of special police unit.
Mossberg 500
A police officer of Commissioner Lorneau's group is armed with a Mossberg 500 shotgun.
Winchester Model 1300
What appears to be a Winchester Model 1300 is seen in hands of another police officer of Commissioner Lorneau's group.
Unidentified pump action shotguns
Double Barreled Coach Gun
A kind of Coach Gun is used by Eric Chaelle's henchman.
Other Weapons
Hand Grenade
An officer of special police unit has a hand grenade, most likely some smoke or flashbang model.