from $10 to $1400 if it is nice. You left out too many variables to receive a more accurate answer.
1000.00 20 ga.
100-400 USD
10-100 USD.
your browning auto-5 lightweight 20 ga was made in 1963.As to value they are going between 450-650 dollars depending on condition.
185 d Model 20 ga Mossberg Whats the Value
50-100 USD
100 - 150 or so
50-500 usd
100-200 USD
100-1000 USD
about 150
The 20 ga shotgun was created by reaming-out the 50 cal. militery musket. I have only seen one.