The signature pistols of Léon (Jean Reno) are Beretta 92FS's fitted with compensators and, in some scenes, sound suppressors. A compensator reduces the rising of the barrel during rapid fire by redirecting propellant gases. We briefly see Mathilda (Natalie Portman) assembling Léon's Beretta 92FS pistols, although we never see her take a shot. The combination of a suppressor and compensator might be considered nonsensical. A suppressor is supposed to re-route and slow the release of pressurized gases from the muzzle in order to reduce the muzzle blast, while a recoil compensator functions by changing the vector at which the gases are released in order to reduce recoil. The problem is solved when it is revealed that one of Léon's suppressors has extended threads which clearly reach past the compensator ports when fitted. One of Léon's Berettas features a two-toned finish with a stainless frame.
SIG-Sauer P226
A SIG-Sauer P226 is used by Stansfield's 3rd man Benny (Keith A. Glascoe) as his duty weapon. It has some sort of laser aiming module mounted under the barrel.
SIG-Sauer P226 (Two-tone)
Léon dual-wields a two-tone SIG-Sauer P226 pistol fitted with suppressor along with one of his Beretta 92FS's during a confrontation with Malky (Peter Appel).
Smith & Wesson 3913/3914
A two-tone Smith & Wesson automatic pistol is seen in the hands Jordan, Stansfield's 4th man. It appears to be a stainless Smith & Wesson 3913 frame with a blued Smith & Wesson 3914 slide.
Beretta 92FS Inox
Léon keeps a Beretta 92FS Inox in his case along with his other equipment.
During Léon's (Jean Reno) opening hit, a pair of the Fatman's (Frank Senger) bodyguards are armed with Beretta 93R machine pistols.
Custom Springfield Armory M1911-A1
Mathilda's (Natalie Portman) pistol is a Springfield Armory M1911-A1 fitted with a compensator and loaded with simunition paintball rounds. She uses it to shoot a drug dealer during her first "hit", fitting it with a suppressor that cancels out the compensator like with Léon's Berettas. She brings it with her when she goes to the DEA building planning to kill Stansfield (Gary Oldman). It is assumed she has it loaded with live ammunition, since simunition would prove useless for killing. Willi Blood (Willi One Blood) refers to it as "Another Nine-Milley," slang for 9mm.
Springfield M1911-A2 SASS
Léon's (Jean Reno) case is packed with a Colt M1911A1 pistol with a nickel finish and combat hammer fitted with a Springfield Armory M1911-A2 SASS upper conversion kit. This conversion turns the 1911 into a single shot pistol in a variety of calibers.
Llama M-87
Mathilda takes along a Llama M-87 with extended controls (magazine release and safety lever) and a compensator, when she goes to kill Stansfield. The Llama M-87 is a competition version of the Llama M-82.
Glock 17
A Glock 17 is holstered on the ESU uniform Leon steals.
Revolvers
Smith & Wesson Model 629 "Classic Hunter" Custom
Norman Stansfield (Gary Oldman) keeps a Smith & Wesson Model 629 revolver with a 3" barrel and unfluted cylinder as his duty sidearm. Stansfield's Smith & Wesson Model 629 appears to be customized or at least a rare, non-catalogued special production run. The standard and/or limited production, short barreled 629s usually have slightly shorter ejector rods (while the gun in the film's ends at the barrel). The muzzle is nicely crowned, too. It's done in a manner uncommon on factory-standard Smith & Wesson revolvers (and limited production runs), which means it was likely a customized & shortened Smith & Wesson Model 629 "Classic Hunter". Unlike the standard model 629, the "Classic Hunter" variation was a special production run made in limited quantities in the late 1980's/early 1990's. It could be had in carbon blue steel and in stainless steel, came with an unfluted cylinder (standard production 629s feature fluted cylinders) and had either in 6-inch and 8 3/8-inch barrel length with the full underlug. Since the 629 "Classic Hunter" Stansfield packs isn't in factory configuration, we can assume it has been further customized and shortened, perhaps to make it more concealable and lighter to carry all-day like an oversized snub nose. The S&W product code is Production Code 103650. Only 3200 were produced in 1989. It had a Round Butt, 6 round UNFLUTED cylinder, Stainless Finish, and 3" Full Lug Barrel. Reference page 260 of the Standard Catalog of Smith & Wesson. The one Stansfield is carrying certainly looks like a custom shortened barrel Classic Hunter rather than this production model although the latter is very similar.
Ruger SP101
Léon (Jean Reno) has a long-barreled Ruger SP101 in his case among his collection of weapons. He gives it to Mathilda (Natalie Portman) when telling her to leave and be a "cleaner" on her own, resulting in her walking to the window and emptying the gun (although she fires six shots when the revolver only holds five). Later in the film Matilda tries to see if Léon really cares about her, so she loads three chambers, leave two empty, and plays the very difficult version of Russian Roulette. Léon tells her he could hear that there was a bullet in the chamber (not likely), but she continues and nearly kills herself before he knocks the gun away.
During the attack on Mathilda's (Natalie Portman) family's apartment one of Stansfield's (Gary Oldman) men, Willi Blood (Willi One Blood) is armed with a Kimel AP-9 fitted with a 20-round magazine which he uses to kill Mathilda's little brother.
IMI Micro Uzi
Several of the Fatman's (Frank Senger) guards are armed with IMI Micro Uzis. At one point he ineffectively wields one himself.
IMI Mini Uzi
The Fatman (Frank Senger) arms himself with a pair of IMI Mini Uzis after emptying his IMI Micro Uzi. He is held at knife point by Léon (Jean Reno) before he can use them. ESU members at the end of the film are also seen armed with them.
Skorpion SA Vz 82
A suppressed Skorpion SA Vz 82 is wielded by one of Stansfield's DEA Agents (Don Creech) after Mathilda's family is killed. It can be noted as the 9x18mm model Vz 82 by its straight magazine, unlike the curved magazine of the .32 ACP Skorpion SA Vz 61.
Spectre M4
A Spectre M4 is seen among the weapons in Léon's gun case. In the extended cut version, we see Léon cocking the weapon, as Léon recognizes the image based on the sound of a weapon cocking a drug dealer's apartment, which is not actually a Spectre M4 itself.
Shotguns
Ithaca 37
Norman Stansfield (Gary Oldman) uses an Ithaca 37 with a tactical flashlight mounted on the pump forend, and fitted with a pistol grip while raiding Mathilda's (Natalie Portman) house. Malky (Peter Appel) also uses an Ithaca 37 with an extended magazine tube.
Remington 870
Mathilda's father (Michael Badalucco) pulls a Remington 870 Slug Gun shotgun on Stansfield (Gary Oldman) and shoots him in the shoulder during the attack on his apartment, as well as killing another henchmen with a shot to the back. (It is loaded with buckshot in the story, since despite being a slug gun, people are impacted by buckshot when shot by it). We also see a Remington 870 on the gun rack in the Fatman's house, and an ESU member is seen wielding one during the final shootout.
Rifles
SGW Multimatch AR-15
Léon requests a rifle from Tony (Danny Aiello) to train Mathilda (Natalie Portman) on her long range sniping exercise. Tony had one of his workers go into the freezer and pull out an SGW Multimatch AR-15 rifle. Mathilda uses the rifle (loaded with simunition paintball rounds) in her practice "hit" on the jogging politician (Denis Bellocq) in Central Park. Simunition is a trademark for training ammunition produced by General Dynamics - Ordnance and Tactical Systems Canada Inc. of Québec, Canada. Simunition encompasses many types of training rounds, the best-known being the FX Marking Cartridge, or paintball round.
Simunition rounds are designed to be used by police and military for training purposes. Most simunition cartridges require slight modification to the weapon to ensure that normal service rounds cannot be fired during training and to simulate full recoil with reduced-pressure/reduced-velocity rounds for more realistic training. In this case for a 5.56 simunition round to work all it would take is a bolt swap to allow this rifle to function with simunition rounds. The prop itself is a slightly modified SGW Multimatch AR-15 and it's very unlikely it actually fired the simunition in the actual movie although it is very possible that it could in real life. Simunition is used only for CQB training, as there is no way any paint round could reach the velocity to hit a target at the distance the movie claimed the hit was made at. Even though the politician was made to look very far the reticle image would prove that the politician was closer than 150 yards, well within the simunition maximum range of 200 yards.
The rifle is the old model SGW Multimatch before SGW turned into what is now known as Olympic Arms. With a 16" medium heavy weight barrel, shaved gas block, carbine length free floating aluminum handguard tube, and a Bell & Carlson AR-15 Thumbhole stock. It has blued 20-round magazines (the kind available in the early 1990s), a Harris Bipod, and a dummy short 'suppressor' for the end of the threaded barrel. The scope is a Burris with a 40mm objective lense, and sits on Weaver's tall see-through scope mount rings.
An ESU member is armed with a SIG SG 551 during the second Assault on Léon's Apartment.
Beretta SC-70/223
Several ESU members can be seen armed with Beretta SC-70/223s, distinguished from the AR-70/.233 model by their folding stocks.
Ruger Mini-14 GB-F
The Ruger Mini-14 GB-F is seen in the hands of NYPD ESU officers who arrive at Léon's apartment during the final shootout.
IMI Galil AR
One of the ESU officers in the first team that enters Léon's apartment is armed with a IMI Galil AR. Strangely enough, this rifle has a wood fore-end instead of the usual polymer, which is rare since they were only made of wood for a short time before being changed.
Armi-Jaeger AP-15 w/ Fake Grenade Launcher
The Armi-Jager AP-15 is seen in the hands of a few ESU officers after the big fight. This could presumably be the same fake grenade launcher in Besson's Nikita.
A heavily modified French MAS AA-52 GPMG with the carry handle removed, a tripod, a Russian PSO-1 scope and a variety of other tactical "junk" fitted is utilized by the ESU team to launch a grenade into Léon's apartment towards the end of the film. The belt-fed machine gun is an absurd weapon for a SWAT-style unit to be equipped with (especially just to launch a rifle grenade), and appears to have been used purely for visual effect. Note that the rifle grenade is not a fragmentation grenade, but rather a parachute flare.
Miscellaneous
Suppressors
Note the third suppressor from the right with its abnormally long threading to bypass the compensator on Leon's Beretta 92FS.
ESU members use M18 smoke grenades during the end of the assault on the apartment. It is likely meant to be a CS grenade ... though no actor would go through that.