Unknown
It will be marked on the barrel.
There are 2 variations of the Tempest. If it is Marked "Tempest" then it was made between 1979-81, if it is marked "Webley Tempest" it was made between 1981-2005
Probably turn of the century
inside reciever stamped: 4256 D C
Depends on what is marked on the gun.
It will be marked on the barrel. The barrel is marked "Made in Portugal".
50-100 USD or so
The current Barrett Firearms does not make a double shotgun. Exactly how is your gun marked?
Definately not. I can't think of any offhand that can, but if it is not marked on the barrel then it cannot shoot them.
Liege, Belgium Superior proof mark A smokeless powder proof
The value of a London Fine Damascus 14 gauge double barrel shotgun marked JT Sang Ford depend on its condition. This gun in excellent condition is valued between 225.00 and 320.00 as of 2014.
No way to tell without the maker's name, and even then data might not be published.