I'm not wasting any time, here we go:
One of the main characters, Martin Riggs (Mel Gibson), carries a Beretta 92F without a holster by sticking it in his waistband at various locations. He loads it at the beginning of the movie by jamming in a magazine and dropping the slide, then sticking his spare magazine in his right rear pocket where it will be useless to him for a quick reload. He later goes to kill a madman and he has to rack a round into the breach. He is then clearly carrying his spare magazine in the front of his waistband:
That's a good way to loose your gear.
The madman he kills is shooting at random with a M1A1 rifle in a horrible chicken wing stance, and the rifle is later shown to be made of rubber:
The cops surounding the place have S&W Model 27s; at least one of which is carried in an open top holster with exposed trigger:
As Riggs is leaving, SWAT shows up with Colt M16s, H&K MP5s, Remington 870s; which one of the officers uses to flag Riggs' face with:
Riggs then goes on and gets into a gunfight with three BGs; one of which (and the first to die) has what looks like a Mossberg 500, but I can't tell if it's a pistol grip or not:
The second has an unknown revolver, and the third has what can only be a FN Barracuda, but curiously has an adjustable rear sight, and it looks as though the spur on the outside of the trigger guard has been removed. I don't think there's a similar gun out there that I missed:
All of the cops backing Riggs up appear to have S&W Model 36s, like this woman's:
We find out that Riggs is a suicidal psycho. He wants to blow his brain out, but can't pull the trigger. Here is the "special bullet" that he has to do the deed:
The bullet is a Federal Full Metal Jacket (FMJ) judging by the casehead seen moments later. What's odd about this is that later Riggs tells his new partner, Rodger Murtaugh (Danny Glover) about how he thinks about killing himself:
"Do you want to hear that sometimes I think about eating a bullet, eh? Well, I do . . I do . . . I even got a special one for the occasion. . . with a hollow point. . . look [shows a bullet that's obviously not a hollow point] . . make sure it blows the back of my godamned head out & do the job right."Then Murtaugh gives Riggs his S&W Model 19 and tempts him to kill himself right there on the spot:
Murtaugh carries that Model 19 in a bizarre crossdraw position with a leather retention holster, and two speed loader pouches on his weak side:
Later he moves it to a more manageable position:
Next we have Riggs and Murtaugh at the firing range, and Murtaugh seems satisfied to only fire six rounds; like that's going to keep his skills sharp. Both of them flinch badly with every shot, like Riggs here who actully fires two rounds without opening his eyes:
Somehow I caught that Riggs fires only nine rounds, but his target has sixteen holes in it:
Riggs and Murtaugh go to talk to someone about the case that they're on when they get into a tangle with an armed guy by a pool. Murtaugh shoots him in the leg with his S&W 19, but then the guy gets up and pulls a Walther PPK:
Riggs kills him dead.
Next, Murtaugh is investigating a war buddy about the circumstances of his [war buddy's] daughters murder when "Mr. Joshua" (Gary Busy) kills the guy with a scoped GAU-5A/A:
Not long after, Riggs gets shot by Mr. Joshua, who uses this unkown shotgun which looks like a Remington 870, but there's not enough there to tell for sure:
Riggs' kevlar vest stops the buckshot.
Murtaugh finds out his daughter has been kidnapped, so him and Riggs hatch a stupid plan to try to negotiate her release without backup. Riggs is dropped off on the side of the dirt road to snipe with this H&K PSG 1 clone:
Murtaugh has a M61 hand grenade which turns out to be a "smoker."
Mr. Joshua's henchmen are armed with a variety of weapons: like this IMI UZI, and this weeks mystery gun:
What is that gun on the right?
Here are a couple more henchmen armed with a H&K MP5 and an unknown AR variant, and another IMI UZI with another AR variant:
Mr. Joshua's men capture Riggs and Murtaugh, but they escape and kill off the rest of the BGs. Riggs grabs a guy's blued Colt 1911 and kills a guy who is also armed with a 1911:
Anyone who loves 1911s knows that if you hold it like this you're gonna get slide bite:
Riggs stuffs the Colt in the backside of his waistband, his Beretta 92F in the front of his waistband, and then grabs a scoped H&K MP5. Murtaugh grabs his Model 19 and a 1911, then they head out of the building. What's strange is that they're in a the back end of a club, and when they come through the door into the bar, Riggs fires one shot which kills the bartender and nobody even notices. It's after he shoots another guy that the room panics.
Mr. Joshua hip fires at them down a hallway with the scoped rifle in this odd hold:
Why can't actors use sights?
As Riggs and Murtaugh go outside the club, Mr. Joshua opens up with his rifle and doesn't flinch the first little but despite firing that thing inside of a car while it's basically in his lap:
Here's the best shot I could get of the scoped H&K MP5 that Riggs has:
Here's Riggs hip firing a scoped weapon at a target that's about 100 yards distant:
Sights! Sights! Damnit, use the freaking sights!
After all that, the general - who is Mr. Joshua's boss - grabs a H&K P7 and some M61 grenades from a bag that includes a H&K MP5:
This is a good closeup of the GAU-5A/A that Mr. Joshua uses:
The last picture I have for you is of a uniformed cop who is wearing a holstered Colt 1911. You have to look closely through the car window:
Sorry for the delay on my post. I'm finishing my basement and it's going slower than I had anticipated. I hope you enjoyed it!
Update: I've done more research on the large snubby that looks like a FN Barracuda, because from what I've read FN never made them with adjustable sights, and now it's pretty obvious it's a Astra .44 Magnum 'Terminator.' There seems to be only one picture of this thing in existence, and you can see it here or here. What an obscure gun!
Update: As pointed out by Taylor in comments, the madman at the beginning has an M1A, not an M1A1. Thank you for the catch!