The following firearms were used in the movie Equilibrium:
Beretta 92FS (modified)
Heavily modified Beretta 92FS pistols are used by John Preston (Christian Bale), Andrew Brandt (Taye Diggs), DuPont (Angus Macfadyen), Errol Partridge (Sean Bean), and the rest of the Grammaton Clerics throughout the film. The versions used in the movie were converted to automatic with a drop-in auto sear (DIAS) and given longer barrels and modified slides. The non-firing versions also had a selector switch on the side (which does not appear on the firing or "practical" weapons).
The weapons are definitely the 92FS and NOT, contrary to popular belief, the Beretta 93R. The 93R is based on the older model 92-series pistols and still has the frame-mounted safety (whereas the weapons in this movie clearly have the slide-mounted safety) and a folding grip attached to the trigger guard (missing from the weapons in the movie). Although the 92FS is not normally a fully-automatic firearm, conversions are possible with DIAS units and have been done for many Hollywood movies (including Judge Dredd and Underworld).
Heckler & Koch G36
The Heckler & Koch G36 is used by many Sweepers throughout the movie, and by Brandt (Taye Diggs) during one of the raids. Preston (Christian Bale) also briefly uses a G36 to kill several guards at the end.
Heckler & Koch G36K
The shorter Heckler & Koch G36K is also used by some of the Sweepers.
Heckler & Koch MP5A3
Heckler & Koch MP5A3s are used by some of the sweepers in the movie.
Heckler & Koch MP5K
A Heckler & Koch MP5K is used by a Sweeper on a motorcycle in one scene and a resistance fighter in the lights out scene.
Walther WA 2000
The Walther WA 2000 is used by a heavily armored Sweeper during one of the raids. Although the weapon is a semi-automatic sniper rifle, it is wielded as though it were a shotgun; the scope and bipod have been removed, and the actor playing the Sweeper pretends to rack a non-existent pump action under the barrel (accompanied by the sound of a shotgun being cocked). The WA 2000 in this movie is also a replica of some sort. It doesn't carry any trademarks at all.
The AKMS is used by several of the resistance members.
IMI Micro Uzi
The IMI Micro Uzi is used by some resistance members.
IMI Mini Uzi
The IMI Mini Uzi is used by some resistance members.
SA Vz.61 Skorpion
The SA Vz.61 Skorpion is used by some of the resistance members.
Mossberg 500 Cruiser
Several of the sweepers are armed with Benelli M3s fitted with forward pistol grips and entry lights.
An M16A2 is briefly seen in the hands of a Sweeper whom Preston (Christian Bale) attacks when his wife is arrested which he drops immediately before snatching an AR-70 from another sweeper, commonly attributed as a continuity error though it is simply seen as one since the maneuver is so fast. When Preston is in the Warehouse raid whipping a group of Sweepers - they use AR-70s, but in some shots, they all clearly have M16A2s instead.
Beretta AR-70/223s are used by many of the Sweepers throughout the film.
The Walther MPK submachine gun is used by many Sweepers in the film.
The Walther MPL submachine gun is used by many Sweepers in the film.
FN P90s are used by the Sweepers in white suits; these particular weapons are clearly rubber props, as evidenced by the fact that even the magazines (which are transparent on a real P90) are solid black. Kurt Wimmer mentions on the DVD commentary that originally, all of the Sweepers were supposed to use the P90, but the Belgian government did not supply the real live-fire P90s it had promised to the production, only rubber training versions. Most of the weapons used by the Sweepers are, therefore, guns that were loaned by the German government (including the H&K G36s, H&K MP5s, and Walther MPKs).
Most Armored Sweepers and police in the movie use Glock 17 pistols as their sidearms. Mary O'Brien (Emily Watson) manages to grab one of these pistols from a Sweeper and tries to kill Preston with it before the Sweeper regains control of his weapon.
A SIG P228 can be seen very briefly in the hands of a resistance fighter killed by Preston.
The Walther P99 is seen on a couple of armored sweeper's vests.
The Uzi submachine gun can be seen being wielded by a resistance member in the ending when the resistance rise up and overrun the Librian Government buildings.
An armored sweeper who's guarding the dog pen is armed with what appears to be a Ruger Mini-14 with synthetic furniture.
A CAR-15 type Rifle fitted with a scope is seen in the "lights out" scene in the hands of several dying resistance fighters.
Snubnose, Bobbed hammer Smith & Wesson Model 10
A Resistance fighter attempts to shoot Preston in the back of the head with a snubnose, bobbed hammer (double action only) Smith & Wesson Model 10.
A likely fictional set of machine guns mounted on top of a Librian APC.
The Beretta M12 can be seen at the end of the film when the resistance storms the Government.
Sten Mk II
The Sten Mk II can be seen at the end of the film along side the Beretta M12 storming the Government. This can be an understandable firearm for the resistance to have as it is relatively simple and was made by hand by resistance groups in WW II. Note that the men are holding the Sten by the magazine which would damage the feeding lip causing the gun to missfire and damage the magazine.
Heckler & Koch G3A4
The G3A4 is seen in the hands of the resistance and in their arsenal.
Steyr MPi 69/81
The Steyr MPi 69/81 can be seen briefly being fired by a resistance fighter in the end.
After all the resistance fighters in the first raid have been killed 2 flamethrower wielding sweepers come in to burn the Mona Lisa.