No published sn data in English
If you have a common shotgun made before 1968, there probably is no serial number to look up. If the serial number is not on the receiver some where; i.e., water table, side, bottom, somewhere; then it doesn't have one & that is as far as you can take the serial number of a shotgun made before 1968.
look on the breach, barrel.
Look on the receiver and barrel.
Look by the release lever.
Check the receiver
You can look up the serial number at Proofhouse.com
277707 is your serial number so what does your car look like? Are you serious? The question can't be answered in its present form.
Proofhouse.com has sn data.
Look on bottom of receiver and barrel
That's not a Sweet Sixteen serial number. In fact, it doesn't even look like a Browning number to me.
Open the barrels and look on the flat part of the watertable (the flat part of the frame where the barrels close up) or the bottom of the barrels for the serial number
This question can't be answered as serial numbers are not unique to a single firearm. Many manufacturers could have made a firearm with that serial number. The only way to answer this is to have a knowledgeable person look at the shotgun - most makers identified their product somewhere.