A Mafia member arriving at the Apalachin conference in 1957 pulls out his M1911A1 and threatens a cow that won't move away from his expensive car.
Thompson M1
The FBI agents and New York state police officers carry Thompson M1s during the opening sequence depicting the 1957 raid of the Mafia's meeting in Apalachin.
During Paul Vitti's opening narration about the Apalachin raid, he says his father (Bart Tangredi) used a ".44 cannon" (most likely a Smith & Wesson Model 29) to hijack a tractor from an upstate New York farmer.
Walther PPK/S
The hitman (Mickey Bruno) sent by Primo to kill Paul Vitti (Robert De Niro) in Miami carries a suppressed Walther PPK/S. After Vitti knocks out the hitman, he picks up the pistol himself.
Paul Vitti (Robert De Niro) uses a Beretta Cheetah during Dr. Ben Sobel's (Billy Crystal) mock execution. When Vitti is unable to fire back at the rival mobsters, Sobel himself uses the gun to take out, as Jelly later tells him, a "'72 Chevy and the Amana side-by-side refridgerator".
AK variants
The two hitmen sent by Primo to kill Vitti at the garbage dump carry AKM assault rifles variants.
AR-15/M16 variants
Several mobsters, including one guarding the door and one hired by Vitti, carry M16 variants at the meeting.
Beretta 92FS
Primo Sidone (Chazz Palminteri) draws what appears to be a Beretta 92FS to threaten Dr. Ben Sobel and later to take a shot at Paul Vitti.
Ithaca 37
One of Vitti's men at the end pulls out an Ithaca 37 with an extended magazine tube and rifle sights to intimidate Primo.
M60
Two mobsters carry an M60 machine gun and extra ammunition, which Sobel later comments to Vitti on.
Glock 19
An FBI agent arresting Primo Sidone and his men in the finale carries a Glock 19.