Provide a detailed description of ALL markings.
By the serial number.
All Brownings have serial numbers.
Comparison to known serial numbers.
You will have to call Browning.
The earlier the better. 1 is in the Browning Museum.
1981
Go to the link below for Browning's web site to date your gun
You will need to supply the serial numbers to your shotguns to get the age of your browning shotguns correctly.
Your question cannot be answered,without you providing a serial number(to determine the age)of your shotgun.
The suffix of M71 was assigned to the Browning model BAR(Browning semi-auto rifle) which was made in the year 1971 in Belgium for Browning.
Please provide the model information. Serial numbers were sequential by model only.
50-500 usd