Like others advised its a 1979 Citori, 12ga, Grade 1, with 3"chambers... You can get the info from Browning web site.
Its the 1979 version of today's Lightning model - that lists new for $ 1,900
http://www.browning.com/products/ca...type_id=461&content=citori-lightning-firearms
But I have a couple of issues / questions on your gun .....
1. Browning introduced their first Invector screw in choke system in about 1983 ....so its not likely a gun built in 1979 has factory screw in chokes ?? If it doesn't have screw in changeable chokes - the barrels will each be marked / on the sides - where they connect to the receiver - with a star pattern... If it in fact has screw in chokes in it - take one out / and tell us what they say on them - who made them, etc ...
2. The older Citori Grade 1's / and the newer Lightning versions - are primarily mfg'd and marketed as "field" guns ....with angled stocks and 26" or 28" barrels. A 30" barrel on a "field grade" Citori in 1979 - would be very unusal. Are you sure its factory marked as a 30" barrel.
I have a few Citori Grade 1's - bought one new in 1988 - that has the Invector screw in chokes for about $ 700. I've also bought a couple more of the same vintage used. We need to know more about your gun ....
If it does not have screw in chokes - value will depend on how its choked ---but value is about $ 500 - $ 600 on a fixed choke gun in good condition.
If it has screw in chokes - it depends on what they are - but value in excellent condition can be around $1,000. If it has some scratches and some handling marks - value can drop $100 or $ 200 ...a photo would help.
But if you can answer the above questions - it will help us tell you what you have.