No way to tell from your description. Your "excellent" might be someone elses "fine" or "very good". Check the auction sites to see if you can find a similar one.
Need a detailed description of finish, condition, box, papers, all features and markings.
500 USD
$400-$500 in excellent condition.
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.
050-1000 usd
Impossible to answer without a detailed description and the serial number.
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