For what its worth , I purchased a Lew Horton 686 in the late seventies , had a 2" barrel along with some other special attractions. Shortly after I bought it , I got a card in the mail telling me about a recall...I did send it in , and modifications were made , along with the " M " stamped on the crane. Can't remember what that recall was for... Perhaps this was the same recall...point is , this was the stainless 686 version.
regards , irold