This is a First Model 44 Double Action Revolver a.k.a. the Double Action Frontier. Caliber is 44-40 with 6" barrel, 1-9/16" cylinder, nickel finish, and hard rubber grips. Low antique serial number in the 6,000 range. Patent dates on barrel run from 1865 up to 1880. 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 one the day he was shot at the Acme Saloon in El Paso, TX on August 19, 1895. See pg. 238, 9th Ed. of Flayderman's Guide to Antique American Firearms.
Overall, NRA Antique Fine+ to Excellent Condition. The nickel plating is factory original with the frame holding 93%, 95% cylinder, and 75% on the barrel. The trigger and hammer both show bright original case colors with strong original blue on the trigger guard and barrel latch. Hard rubber grips are very nice with no chips, sharp checkering, and perfect metal fit. Only flaw is a small crack on the upper panel of the right grip. I didn't even see it until we photographed it. Action is in good working order. Barrel to frame locks up well with just the slightest hint of play. Ejector works flawlessly. Bore is Very Good overall. A nice example of an early large frame Smith and Wesson DA Frontier revolver.