In Lethal Weapon, his police issued sidearm was his Beretta 92F. In Lethal Weapon 2 and beyond, his sidearm is a Beretta 92FS. Riggs has killed more people with this type of weapon than any other character in the series.
In a director's cut scene, Martin Riggs draws his gun on the school sniper. He shoots about 6-7 times, killing him and ending the shooting.
Riggs later takes out the gun out of his pocket in front of the drug dealers, revealing his true intentions for being with them. He takes out the sniper hiding behind the Christmas trees before wounding one of the drug dealers. While pursuing the other, the conscious drug dealer takes his Beretta 92F and he surrenders him at gun point.
Riggs would attempt suicide with his Beretta and loaded the chamber with a hollow point bullet. After a while, tearfully suffering the loneliness from his deceased wife for four years, Riggs makes the right choice and decides to live.
Riggs uses his gun again when the pimp they were trying to question was about to kill Roger Murtaugh. He whacks the gun out of his hand then shoots him three times as he falls into the pool.
In the climactic scene where Martin Riggs defeats Joshua, a tired and exhausted Riggs, together with Murtaugh, pulls out his Beretta 92F to kill Joshua before his own life would be taken.
In the sequel, Martin Riggs ditches his 92F in favor of the more improved and advanced Beretta 92FS.
While aboard a suspect's stolen vehicle, Riggs grabs his gun out and tells the suspect to surrender, but he quickly turns the wheels and shook the gun out of Riggs' hand. Leo Getz picks up his dropped gun and when he returns to Roger Murtaugh's car, the latter takes it away from him for safety.
During a sneak in visit to Arjen Rudd's office, Riggs plays "Eeny, meeny, miny, moe" with him and his henchmen, pointing his pistol at every one of them, but shoots his fish tank instead to scare him.
Following an attempted murder on Riggs at his trailer, he brings out his Beretta and takes aim on two of Rudd's masked henchmen while on ground, while making a run for it with Rika, he shot the helicopter with it. He would later use it again on a raid aboard the Alba Varden cargo ship killing henchmen, before confronting Pieter Vorstedt.
In the third film, Riggs first shows Murtaugh, Edwards, and some other officers at the shooting range an armor piercing "cop killer" bullet being shot from his pistol in how it can penetrate a bullet-proof vest.
Riggs draws his pistol when he orders a group of African-American gangsters he catches dealing cocaine to surrender. When one of the gangsters surprises Riggs with gunfire, he attempts to shoot at them, but is hit in the back by another one.
At a warehouse, Riggs aims his gun as usual at an opponent until he sees it is a dog. Rather than kill the Rottweiler, he puts his gun away and tames it.
Riggs draws his Beretta once more during a shootout with Jack Travis' men in the subway construction underground. At one point, he dual wields two of the same pistols after taking one from his fallen partner Officer Edwards.
He would later use it during the blazing shootout with Travis' henchmen to subsequently end his arms dealing operations.
Martin Riggs has equipped his Beretta pistol with a laser aim pointer. This comes in handy in certain scenes of the film. When a barge carrying illegal Chinese immigrants passes by, Riggs boards it and goes to check what the noise was up there. Encountering a Triad gang member, he tries shooting him, but misses every time. Using the recently upgraded laser accessory of his pistol, Riggs aims it at a deflectable piece of metal and hits him in the rear, then fatally shoots his chest.
He later uses his gun when he aims the laser at one of Uncle Benny Chan's henchmen and distracts him from hurting anyone. Then, in a struggle with Wah Sing Ku, he dismantles the slide of Riggs' Beretta in one deft move rendering it useless.
Later on, Riggs either got his Beretta fixed or purchased a new one. He would use it during the final battle with Ku and his henchmen, as well as against the Four Fathers.
A Beretta 92FS Inox also appears in the series. It is simply a stainless version of a typical 92FS only it is silver in appearance and it is not seen in Martin Riggs' possession.
In Lethal Weapon 3, Hatchett is seen with a Beretta 92FS Inox in his hand through much of the scenes he is in. He pistol whips Smitty with it as he falls into a concrete pit, and he also uses it to fire at Riggs and Cole, who escape with the confiscated firearms escaping the warehouse.
Jerry Collins is seen carrying a Beretta 92 SB-C during the botched attempt at arresting the diplomats in Arjen Rudd's house.