First, it is not a machine gun, regardless of how it is marked. Second, most likely made around the turn of the century.
Check the barrel and receiver
Impossible to answer without the serial number.
could be the serial number or an assembly number.
Entirely possible.
1968
By the serial number.
You did not provide a serial number. You will have to call Browning.
Serial number 1
by the serial number on the bottom of the receiver
You did not provide the serial number.
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.
No serial number provided.