A Glock 23 is the sidearm carried by Boston PD Detective Thomas Craven (Mel Gibson) throughout the film. He uses it on multiple occasions, most notably to dispatch some of Northmoor's private security personnel working for Jack Bennet (Danny Huston). When Craven enters David Burnham's apartment, you can clearly see the slide, which says "23".
Thomas Craven (Mel Gibson) finds a Springfield Ultra Compact with Hogue rubber grips from Emma Craven's (Bojana Novakovic) bedroom. The firearm belongs to Emma's boyfriend Dan Burnham (Shawn Roberts). Craven later gives this firearm back to Burnham to protect himself.
Northmoor's private security officers, including Jack Bennett's bodyguards Agent One (Frank Grillo) and Agent Two (Peter Epstein) all carry SIG-Sauer P220R pistols as their sidearms. Craven (Mel Gibson) also takes one from Bennett's driver and uses it to scare him.
Jack Bennett (Danny Huston) uses what appears to be a Smith & Wesson Model 19 Snub Nose during the climactic firefight. This is the only frame in which the revolver is visible and it's very fast so the screencap quality suffers somewhat.
A sawed-off 12 Gauge Double Barreled Shotgun is used by Agent One (Frank Grillo) to murder Tom Craven's daughter, Emma Craven, at the beginning of the film. One is also seen on a dead hitman's table, who's being used as a fall guy.
