Since you cannot look up the specific date, you must rely on the range of production and specific mechanical features to estimate when your specific 840 was made.
Unlike modern firearms, many Cooey shotguns were produced without serial numbers entirely, particularly those made before the late 1960s. Even when serial numbers are present, there is no centralized official database to provide an exact "born-on" date. Cooey Model 840 Serial Number Lookup
If your receiver is stamped "Made by Winchester-Western (Canada) Limited," it was definitely produced after the 1961 acquisition. 2. Finding the Serial Number (If It Exists) Since you cannot look up the specific date,