Inherited recently a 20" tip up pistol along with many cool Indian items All from my grandmother who resided near a Sioux Indian reservation in the early 1910's. It's stamped Stevens & CO Chicopee Falls, Mass PAT SRPT.E.1864. It has another stamp with the number 1673 on the barrel and the same number on the bottom of the wood/metal handle. The barrel is octagonal, with no color. The main metal housing is a probably nickel plated. There is no trigger guard. I know absolutely nothing about firearms, but saw a few items on the internet to get some basic info. Can anyone help in identifying this pistol as to its beginnings and value range. Thanks.