Serial number on a Citori is under the breakdown lever on the receiver. It should also be stamped on the barrel where it locks up on the receiver.
50-750 usd
50-1000 usd
Depending on condition 200-800 USD.
1972
If you have the money....
12 gauge BSS were first made in 1971 and 20 gauge in 1972.
1986
A Browning side by side 20 gauge shotgun in Grade I,with a original finish of between 70%-90% will bring between 1,000-1,800 dollars.
You must call Browning with the serial number to find out.
1976
Made before 1975