The value will depend on the exact model, features, and condition - information not provided and impossible to adequately describe. The shotgun must be appraised in person by someone who is familiar with guns and, preferrably a collector of FN shotguns. I suggest that you contact a local gunsmith or , by going through the local gun shops, locate a shotgun collector who is willing to appraise it.
Up to 500 USD
Impossable to answer without a description of the condition of your Browning shotgun,and the serial number.
Need model information. You listed the barrel marks on a shotgun that are on many different models. Also need condition and details of the gun.
FN made several models of shotgun. Would need to know what type of action, etc.
Value is too difficult to be accurate without seeing the gun. Condition which includes the amount of original finish and original configuration will determine value. Recommend taking it to a gun shop for appraisal.
Made in 1926
No FN sn data published.
This is an Auto-5 Shotgun
No way to answer since a serial number was not provided.
No sn data available.
Up to 500 USD
No published sn data.
It stand for "national plant of war weapons herstal Belgium" Fabrique National is simply "National Plant" and it is common to call the Company "FN".
FN is the abbreviation for Fabrique Nationale Arms Co. of Herstal, Belgium. They made most of the A-5 shotguns and Superposed shotguns for Browning USA.
No published sn data that I know of for FN
Can't be answered without a DETAILED DESCRIPTION OF ALL MARKINGS and what it is (rifle, handgun, shotgun)
Impossable to answer without a description of the condition of your Browning shotgun,and the serial number.