SN: K633730. 1970's vintage, shoots .22 blanks, 12" barrel. Very rare experimental tranquilizer dart gun made for Mercox, this piece was originally part of the Smith & Wesson Archive collection sold in the 1990's. Based on a model 17 K-22 frame and made to be used with .22 blanks to launch the darts, only 25 of these were made. This is one of the rarest post-war S&W’s made. Excellent condition with box. Includes a copy of an interesting letter from the S&W Sales Manager to Col. Rex Applegate, talking about the history and value of the Mercox at that time, as well as a factory letter explaining the details of this gun. A neat and desirable collectors piece.