Impossible to answer without a detailed description of all markings, finish, barrel legth, action type, condition, accessories, box, papers, etc..
your browning auto-5 lightweight 20 ga was made in 1963.As to value they are going between 450-650 dollars depending on condition.
100-1000 USD
50-500 usd
No
50-500 usd
100-1000 usd
100-1000 depending on specifics
200-1200 usd
50-500 USD range
100-2000 USD or more depending on specifics
100-10000 USD or more depending on specifics
000.000013