AT-1170 Smith & Wesson .32 rime fire NO.2 Old Army revolver
At-1170 Smith & Wesson .32 rime fire
NO.2 Old Army revolver
6" barrel with fair bore
MFG 1867
SN. 55848
The Smith & Wesson Model No. 2 Army a.k.a. Model No. 2 Old Model Smith & Wesson Revolver was Smith & Wesson's first .32 caliber revolver, intended to combine the small size and convenience of the Smith & Wesson Model 1 .22 rimfire with a larger caliber. Chambered in the .32 rimfire long caliber, its cylinder held 6 shots. It was manufactured 1861 - 1874, with a total production of 77,020.
The Smith & Wesson Model 2 Army is a single action tip-up revolver, on which the barrel pivoted upwards, hinged on the forward end of the topstrap. It can be identified by its octagonal barrel, smooth cylinder (lacking fluting) and the flat shape of the grip butt. The revolvers were available in blued or nickel-plated finishes and the majority were produced with 5 or 6-inch barrels. 4-inch barrels were rare and a few revolvers with 8 and 10-inch barrels an extreme rarity.
A difference between the early S & W Army No 2 Model, serial range 1 to about 3000 and later revolvers, is the addition of third pin to the top strap to limit the travel upwards of the cylinder stop.
https://www.atf.gov/firearms/firearms-guides-importation-verification-firearms-national-firearms-act-definitions-antique