As DCWilson suggested, the key piece of information is the serial number on the bottom of the butt. If there is a letter there, like V, VS, S, or C, include it. There should also be the same number stamped on the bottom of the barrel and on the rear face of the cylinder. You should also provide the barrel length (measured from the front face of the cylinder), and list all markings stamped on it. Value is very strongly influenced by condition, so without a series of good pictures showing detail, it is not possible to estimate a value, except over a very wide range, like $100 to $500. $100 would be with little or no original finish, damage, defacement, modified/missing/replaced parts, or in non-working condition. $500 would be for one in complete and original condition that looks much like it did when it left the factory.