There are limited references on the 640K. Mine show the 640K made 1959-1960, the 640K-A from 1960-68, and the 640K-D from 1969-1985. My best guess would be after 1968. Vic Havlin at havlinsales.com runs the Mossberg Collector's Association, and may be able to narrow down the dates.
Chat with our AI personalities