As in all the previous Lethal Weapon films, Detective Martin Riggs (Mel Gibson) carries a Beretta 92FS as his weapon of choice, albeit this time fitted with a laser pointer integrated into the grip. At one point in the film, the pistol is rendered unusable when the lead villain, Wah Sing Ku (Jet Li), manages to field strip the pistol through crafty manipulation of the takedown lever although he seems to have reassembled it afterwards because he is seen weilding it in the final shootout and at the end.
Smith & Wesson Model 19
As in all the previous Lethal Weapon films, Detective Roger Murtaugh (Danny Glover) carries a Smith & Wesson Model 19 revolver as his standard weapon.
OA-93
At the beginning of the film, Riggs and Murtaugh respond to a call of a man dressed in a fireproof suit wreaking havoc with a flame thrower and an OA-93.
What is interesting is that there is a small "pistol" buffer tube attached to the upper receiver of the OA-93. This feature is not part of the OA-93 design, which has a distinctive recoil assembly above the upper receiver which eliminates the need for a buffer tube with spring. Movie armorers had difficulty making the OA-93 cycle blanks, so they added the small buffer tube to the back of the gun, however the original gun doesn't have a buffer tube.
Smith & Wesson 5906
As in the previous two Lethal Weapon films, Detective Murtaugh uses a Smith & Wesson 5906 as his back-up weapon. Detective Riggs also brandishes this weapon during the encounter at Murtaugh's house.
Glock Handgun
During the encounter at Murtaugh's house, one of the Chinese triad gang members can be seen with a Glock handgun of unknown model.
At the beginning of the film, Riggs and Murtaugh respond to a call of a man dressed in a fireproof suit wreaking havoc with a flame thrower, torching anything that comes near.
Gold Cup National Match M1911A1
In several scenes, a rookie officer, Detective Lee Butters (Chris Rock) can be seen wielding a stainless steel Gold Cup National Match M1911A1 as his standard weapon.
Makarov PM
Several members of the Chinese triad can be seen wielding Makarov PM pistols, most notably during the encounter in Murtaugh's house. From closer examination of the pistols, it appears that the Makarovs used by the triads were Chinese-made Norinco copies of the Makarov PM.
Type 56
PLA soldiers escorting the "4 fathers" are armed with Norinco Type 56s along with a smuggler.
Near the end of the film, a three-way gun battle erupts between the protagonists, Chinese triad members, and the private army of a corrupt Chinese General. The General's men can be seen wielding Type 56 and Type 56-1's, one of which Riggs gets ahold of to kill Wah Sing Ku (Jet Li), firing the weapon point-blank while both of them are underwater.
This is definitely either an East German MPi-KMS, or another AKM variant fitted with the East German-style folding stock. -MT2008
AWB poster
Seeing as this film was made in the Clinton era, not long after the enactment of the Assault Weapons Ban there is an AWB propaganda poster in the police station.