50-550 usd
50-600 usd
You can get gun pricing at http://www.UsedPrice.com. They are a good place to start.
100-1000 USD or so
1926; 50-500 usd
If your browning auto-5 is in excellent condition(85-90%)original finish?I would assign a value of 550-650 dollars.
50-575 usd
See what they are selling for at Gunsamerica. http://www.gunsamerica.com/ That should give you a pretty good idea.
50-600 usd
You will have to call Browning with the sn to find out.
This is a mixed question. Which gun do you have? An Auto-5 Light twelve, is not a pump shotgun, it is a semi-automatic. Since 1979 is before the Browning Pump Model BPS was introduced, It is assumed you do have an A5. Value depends on condition. Typically with average use, these guns sell in the range of $500-$750 depending on condition. Mint in the box will go $1000+, but remember that this model has a fixed choke in 1979 and won't bring as much as the later Janaese made Auto-5's. The nickel plating you mention is not Browning factory finished. Browning never plated an auto5. You could have a silver receiver that was custom engraved, but it wouldn't be plated. If someone actually did nickel plate the gun, it could decrease value.
50-550 usd
The value of such light is approximately $10,000