Armand "Blackbird" Degas (Mickey Rourke) uses an M1911A1 as his sidearm in the film. The gun changes between three different guns in different parts of the film, thanks to the extensive re-shoots of the production.
Colt MK IV Series 80
Armand "Blackbird" Vegas' (Mickey Rourke) first 1911 is a Colt MK IV Series 80. He uses it to kill his first target in the film. This gun is also briefly seen tucked in his pants when he's at the Colsons.
Colt M1911A1
The second 1911 Degas uses is an original M1911A1. After Blackbird uses a Colt MK IV Series 80 to the target, his gun changes into an original M1911A1. This gun is the one he uses for the rest of the film, with one exception.
Norinco M1911A1
The third gun Blackbird can bee seen with is a Norinco M1911A1, which is an inexpensive copy of the original gun. Blackbird pulls this gun out, when Richie is trying to rob him, before pairing up with him.
Blackbird's little brother has a Beretta 92FS tucked into his pants during the hospital flashback.
Glock 19
A Glock 19 is seen in a cop's holster, when they are interviewing the Colson's after the first incident with Nix and Blackbird.
Mossberg 500
Lionel (Aldred Montoya) is seen with a Mossberg 500 shotgun when Blackbird returns home to Walpole Island. Lionel also uses the shotgun when he, Richie and Blackbird go duck-hunting. He tries to smack Blackbird with it. During the duck-hunt scene the shotgun turns into a plastic prop.
Remington 870 Slug Gun
Wayne Colson (Thomas Jane) keeps a Remington 870 Slug Gun for protection. He briefly handles it when he picks up some of his stuff from Carmen. He retrieves it after the first incident with Nix and Degas, and waves it around a couple of times when the FBI interviews them. Carmen Colson later uses the shotgun. She tries to use it on Blackbird, but he takes it from her and uses it on Wayne instead.
Winchester Model 1200
Wayne (Thomas Jane) brings a Winchester Model 1200 shotgun with an extended barrel to Carmen (Diane Lane) to keep as protection. She uses it to protect herself when Blackbird comes knocking. Wayne apparently takes the shotgun with him to Missouri when they are put into the witness protection program and keeps it in his car. He uses it against Blackbird in the climax. The gun changes very briefly into a Remington 870 after Wayne's been injured, when he manages to grab the shotgun and fire a fatal shot. Right after that it changes back into the Model 1200.
Remington 870
Richie Nix carries and fires a Remington 870 throughout the film. He most notably uses it at a gas station to try and kill Wayne Colson. He manages to destroy almost all of the store but no to kill Wayne. There's a continuity error when Richie's 870 with wooden furniture briefly turns into a Remington 870 with synthetic furniture. Wayne Colson's Winchester Model 1200 also very briefly changes into a Remington 870 during the climax.