Browning.com has a sn function on their web site that you can use.
On the receiver.
1985
1980
1986
A citori 325
1982
i would go to the browning web site.Click on the customer service link and there should be a spot were you can research your browning citori lightning.
This is a 12ga made in 1973. It is the first year of production for the Citori Model.
Go to Browning's site, click on Support then date your firearm.
It will be marked on the botton of the receiver.
solder
100-1000 USD or so