A character on Little Caesar, the fictional TV show in the film meant to resemble The Sopranos, carries out a mob hit with an Ithaca 37. Jelly (Joe Viterelli) also has one in his armory that he offers to Dr. Sobel before the armored car heist.
LaFrance Specialties M16K
Two mobsters on Little Caesar use LaFrance Specialties M16Ks to carry out a mob hit. That's no M16K. Looks like an M4 or something. It's go the front sight/gas block and a longer barrel than the M16K.--Mandolin 22:13, 25 September 2010 (UTC)
Taurus PT92
A prison guard hired to assassinate Paul Vitti uses a suppressed Taurus PT92. Anthony Bella (Anthony LaPaglia) has a PT92 as "Nicky Caesar" on the set of Little Caesar, seen locked open when he is arguing with the armored car officers in the climax.
Colt Diamondback
Jelly (Joe Viterelli) carries a snubnose Colt Diamondback, drawing it on Eddie DeVol and firing it at a Rigazzi gunman in the restaurant.
Desert Eagle
During Vitti's "limp sword" nightmare he tells Dr. Sobel about, Patti LoPresti (Cathy Moriarty) holds a chrome Desert Eagle on him.
Lou Rigazzi (Frank Gio) uses a suppressed Beretta Cheetah when his men bring the failed gunman into his office. Paul Vitti (Robert De Niro) also carries an unsuppressed Cheetah, drawing it from a hiding place in his trailer on the set of Little Caesar.
MAC-10
One of the gunmen chasing Vitti and Sobel fires a MAC-10 from the window of his car. Jelly also keeps one in his armory that he offers to Sobel.
Glock 17
Paul Vitti (Robert De Niro) keeps a third-generation Glock 17 under his couch cushions in his trailer, which he tosses into a bag when hiding out from the police and Rigazzi's men. "Al Pacino" (William DeMeo) carries one during the planning and execution of the heist. The armored car officers also carry them in holsters.
Smith & Wesson Model 36
Jelly (Joe Viterelli) carries a nickel Smith & Wesson Model 36, which he draws when a Little Caesar crew member enters Vitti's trailer. One of the Little Caesar cast members also uses one during filming.
M60
When Jelly offers a bulletproof vest to Dr. Sobel, an M60 machine gun is visible on the table next to the vest.
M16A2
Jelly has an M16A2 in his collection, asking Dr. Sobel if he can handle an M16. When Sobel asks if he means to shoot it, Jelly sarcastically tells him he wants him to twirl it around his finger.
M4 Carbine
Jelly has two M4 Carbines in his gun collection, between the M16A2 and AKS-74U.
Jelly asks Dr. Sobel if he wants an "AK" or a "Kalashnikov", referring to both the Norinco Type 56 and AKS-74U he has on the table.
Franchi SPAS-12
Jelly keeps a Franchi SPAS-12 with a solid fixed stock/pistol grip combination in his collection.
Uzi
Jelly keeps an Uzi in his gun collection when showing it off to Dr. Sobel.
Colt Python
Dr. Ben Sobel (Billy Crystal) asks Jelly if he can use a nickel snubnose Colt Python instead of one of the larger assault rifles. Jelly holds the gun laughing, remembering a lot of "good times" from the revolver, then hands it to him. Eddie DeVol (Raymond Franza) also carries a blued snubnose model.
Heckler & Koch MP5A3
The armored car officers and fake NYPD ESU officers working for Vitti, have Heckler & Koch MP5A3 submachine guns.
Heckler & Koch MP5SD
One of Vitti's men carries a Heckler & Koch MP5SD during the armored car heist.
Edit: This is an airsoft gun made by UHC. Note the finger groves on the handguard, which no production MP5SD's have.
Remington 870
An armored car guard has a Remington 870, which Vitti's men promptly disarm him of.