Can't really value with just the sn. Range would be 10-1000 USD
YOu must provide the serial number.
The serial number L52789 indicates that you have a Browning light weight model,auto-5 shotgun which was made in the year 1955.
By this serial number for an Auto5, the gun should be a Light Twelve 12 guage model made in 1956. It is not a Sweet 16.
Go to Browning.com and you can download a manual
You will have to call Browning with the serial number.
Your serial number indicates that your Browning light twelve was made in the year 1955.
If your browning auto-5 is in excellent condition(85-90%)original finish?I would assign a value of 550-650 dollars.
Supply your serial number at the Browning website and the database will look it up for you.
It shouldn't say light twelve on the barrel, but on the receiver. Light twelve means that the gun is a light weight version of the standard Auto5 shotgun.
Your browning auto-5 light weight was made by FN of belguim for browning in 1960.
If it is marked Light 12, that is an incomplete serial number.
You will have to contact Browning to find out.