Here you can see the similarities in the lockwork between the Smith & Wesson 640-1 (top) and the Kimber K6S (bottom). The angle of the hammer spring and pushrod has been changed by about
6 degrees and the hammer redesigned to match. Otherwise, the double action sear, the trigger, and the rebound slide are nearly identical. The cylinder lock has been redesigned to extend far to the
right side of the frame. Note the black coating on the K6S hammer and rebound slide.