You will have to provide the serial number. Alternatively, you can call Browning with the serial number and they will tell you. Some serial number information is on line at their website.
1924
1980
1973
Not a valid Browning serial number.
It was made in 1929
1929
Impossible to answer without the serial number.
Your Browning superposed,over under 20 gauge shotgun was made in the year 1951;with the serial number that you have provided.
You will have to call Browning.
The last 2 letters in your serial number NZ indicate that your Browning 325 in 20 gauge was made for browning in the year 1991.
This gun was made in 1950.
1931