Made from 1948 to 1965. It features a rounder receiver.
Early models just list the gauge and shell length (e.g., "3 INCH CHAMBER"). Cooey Model 840 Serial Number Lookup
If you can tell me are on the side of your receiver or if there is a number on the barrel lug , I might be able to help narrow down the production era for you. Can Anyone Date Cooey Shotguns - Year of Mfg. Made from 1948 to 1965