Not necessarily unknown - information from David Carroll indicates that the gunsmith was Joe Lamping of Cincinnati, in the 1940s and '50s. Copy and paste from post #10, in this thread: S&W 1917

"Looks similar to the hammer on a gun modified by Cincinnati gunsmith Joe Lamping. Here's some text and pictures from an old auction on Gunbroker by David Carroll (woodlawn boys):

SMITH & WESSON .44 HAND EJECTOR, 2ND MODEL TARGET -- 6 ½” barrel, original blue finish with non-medallion checkered walnut grips. A fabulous 1924-1925 mfg. revolver that was professionally altered in the late 1940’s or early 1950’s with the installation of a custom-made, solid full-length target-sighted barrel rib. This custom conversion was done by a then well-known Cincinnati, Ohio pistol-smith of the period, Joe Lamping, who was a serious competitive shooter as well. On the new barrel rib Mr. Lamping installed a S&W post-war rear sight assembly and a brass-bead ramp front sight. He also reconfigured the original hammer, added a trigger-stop screw in the trigger guard and honed the action to perfect smoothness. The satin-blue finish is 100% original and shows only light handling and use, the non-medallion grips are original and matching-numbered, the fit and function is flawless and the bore & cylinder chambers are mint. An awesome and very cool post-war period conversion N-frame, done by one of the early master gunsmiths !! Please see the numerous photos for all details and close-up views of the finish condition."