If it is double action, with a visible hammer, it is probably the .38 Double Action, Second Model. It should have double stop notches and long grooves in the cylinder. They were made in both blue and nickel finish. It is not a rare gun (there were around 110,000 made) and there is not much collector interest unless in about perfect condition. Even in top shape, with near 100% original finish, they will only bring about $300. Very few are in even decent shape; most are either badly worn or, if nickeled, have chipped and peeling nickel. Those will fetch maybe $150 if in functional condition.
Jim
