The original "Main with No Name" gun from the Clint Eastwood "Dollars Trilogy" of western films including "A Fistful of Dollars", "For A Few Dollars More" and "The Good, The Bad, and The Ugly.
The Good The Bad And The Ugly
Colt 1851 Navy
Featured in The Good The Bad and The Ugly and carried by both Blondie and Tuco. Blondie's gun features the Snake grips seen on his other guns from previous films and which first appeared in the TV series Rawhide. The film guns were made by Uberti.
In the films the guns change slightly from scene to scene. In most scenes the old fashioned black powder firing ball and cap "Percussion model" pistols are shown which is appropriate for the year the film is set in (1862'ish). But in certain scenes (for example where the gun is being loaded or being shot) a cartridge loading pistol is shown instead. The guns are clearly meant to be "Richards conversion" models that feature center-fire cartridge ammunition like we know of today. It takes a trained eye to tell the difference between the two models from a distance. In all other scenes of the film, the percussion model is shown. In reality the first Richards conversion models weren't made until years later in 1871 after the civil war had already ended.
The converted version of the Colt Navy is what is sold by Cimarron as their recreation of this famous gun.
Blondie and Tuco used conversion models in The Good, The Bad, and The Ugly since the old ball and cap percussion models are extremely slow to reload. Authentic guns would have made for a very different film.
You can watch the long slow process for loading an actual percussion model Colt 1851 Navy here to understand why the original models wouldn't wouldn't have worked very well for the film's characters.
Blondie carries a Colt cartridge revolver which is actually non-historical as it is not actually a "conversion" of a cap and ball revolver but more in the way of a factory cartridge revolver--a conversion revolver has a "filler ring" which mounts the loading gate and a turned-off cylinder however these guns have full length cylinders and loading gates which are factory engineered into the frames. In fact, these revolvers are essentially Model 1872 factory cartridge revolvers except for the fact that a Model 1872 would not be able to mount the Model 1851 barrel. Uberti, then, has created the world's first Model 1851 factory cartridge revolvers by specially machining some raw forgings to become .38 centerfires. Tuco also carries a Cartridge Navy, his being fitted with a lanyard loop, which instead of a holster, is stuck in his pocket (because Eli Wallach had trouble holstering a revolver without looking at the holster.) Angel Eyes also used a Navy Cartridge to murder a sickly old man towards the beginning of the film, firing it through his pillow. He keeps this Navy when serving in the Union, but carries a Remington 1858 for his own use. Throughout the film, it becomes obvious that if they have a cartridge revolver, they are going to fire it in the scene. In any other scene, the revolvers change to unloaded percussion models (with the exception of Blondie's). Cartridge revolvers were being manufactured even this early in the Civil War(see 1861 Prescott Revolver, .38 Rimfire). A rimfire revolver would not actually be an anchronism however Colt never chose to violate the patent while many others did.