This is a First Model .44 Double Action Revolver, a.k.a. the Double Action Frontier. Caliber is 44-40 with 6-1/2" barrel, 1-9/16" cylinder, nickel finish, and hard rubber grips. Low antique serial number in the 4,700 range. Patent dates on barrel run from 1865 up to 1877. Among the more colorful owners of this model was the notorious gunfighter John Wesley Hardin. He is purported to have been holding a nickel plated S&W .44 DA the day he was shot in the Acme Saloon, El Paso, TX on August 19, 1895. See pg. 238, 9th Ed. of Flayderman's Guide to Antique American Firearms.
Overall, NRA Antique Good+ to VG- Condition. The frame retains 40% original nickel plate while the cylinder shows 40%, and the barrel has 65%. The balance has turned over to what is mostly a dark gray patina with some minor spots of light corrosion. Nice markings and good checkering on hammer and barrel latch. Fine screws throughout. Original sights are unaltered. Trigger guard and barrel latch show traces of original blue in protected areas. Matching numbers on the frame, barrel, cylinder, and latch. Original hard rubber grips are in fair condition with the checkering and S&W monograms both visible but showing considerable wear. Left grip shows a tiny crack to the right of the escutcheon but otherwise solid. Very Good bore and mechanics. Decent example of an early S&W Frontier.