All my research indicates that the 9Z prefix to your serial number belongs to the Browning 20 gauge light weight shotgun that was made in the year 1959.If you had a 12 gauge auto-5 magnum shotgun,then the prefix would be 9V.The value of each of these will be between 350-550 dollars,depending on overall condition and a good bore.
$400-$500 in excellent condition.
500 USD
400 or so
300-500 USD.
1903-1939. Value depends on condition. Your definition of excellent might not mean excellent in terms of collectable Browning shotguns. Broad range; a couple of hundred to a couple of thousand.
with these fine made Belgium shotguns,condition is everything in the value of your Browning Sweet Sixteen shotgun which was made in Belgium in the year 1957.They can be worth between 300-1,200 dollars if the original condition is quite prevalent and the bore is in excellent condition.
Impossible to answer without a detailed description and the serial number.
050-1000 usd
About $550 for plain barrel, $850 for vent rib. This is for EXCELLENT condition, lesser condition less $$$.
100-500 USD
Blue Book of Gun Values might help
Your browning auto-5 shotgun was made by FN of belguim for browning in 1938.In the condition that you describe your shotgun should be worth between 450-550 dollars.