You did not provide a serial number. You will have to call Browning.
Your Browning auto-5 shotgun with the prefix of 70s to the serial number identifies that your shotgun was made in Belgium for Browning in the year 1970.
By the serial number.
You will have to call Browning with the sn to find out.
by the serial number on the bottom of the receiver
Serial number 1
Your browning auto-5 shotgun was made by FN of belguim for browning in 1957.
Your sweet sixteen browning auto-5 shotgun was made by FN for browning in 1963.
With the serial number that you provided,and assuming that we are talking about a browning auto-5 shotgun then your shotgun was made by FN of belguim for browning in 1909.
Your belguim made browning auto-5 standard weight shotgun was made in 1962.
It was made in 1949.