For movie characters, bearing arms is not merely a right. It's practically an obligation. Guns are as integral to the movies as training montages, match cuts, and Brian Dennehy. Where, after all, would James Bond have been without his trusty Walther PPK? Or Harry Callahan without his .44 magnum? Let's not forget that one of the defining images of early cinema is that unforgettable shot of Justus D. Barnes firing a gun directly at the camera in The Great Train Robbery (1903), a shot so cool that Martin Scorsese borrowed it for Goodfellas. Well, thanks to a fairly old, but still handily unsettling site called the Internet Movie Firearms Database, you can identify Barnes' weapon of choice as Colt 1878 Double Action Revolver.
The IMFDB is a comumunity-edited, Wikipedia-type site with over 15,000 user-generated articles about the specific types of firearms used in movies and television shows. For detail-oriented movie geeks, the site can be a disturbingly addictive timesuck. It answers all sorts of nagging questions. For instance, what kind of weapon does Donald Pleasance use to shoot Michael Myers in Halloween (1978)? A Smith & Wesson Model 15 Combat Masterpiece, that's what. Are there guns in It's a Wonderful Life? Hell yes there are guns in It's a Wonderful Life! Remember? Bert the Cop brandishes an M1903 Springfield in a World War II flashback and fires a Smith & Wesson Model 10 at George Bailey during the "Potterville" sequence. From Animal House to Zardoz, there are hundreds upon hundreds of articles to peruse. If nothing else, this site might provide you with some tidbit to bring up with your crazy uncle next Thanksgiving.