It's an off-branded Stevens Model 311, worth $150-$250, made between 1920 and 1948.
I got one from e-gunparts.com, which is Numrich. They have schematics for many guns.
This a double barrel shotgun. This is my second favorite shotgun in the world. The reason why it is called 12 Ga double barrel is that the barrel in 12 inches long, and every two shots, it has to be reload.
Depends on what is marked on the gun.
If it is a double, remove barrel and you will see it along with serial #.
thomas jackson of london england
Can't be answered as asked
Blue Book of Gun Values will help.
An older used utility double barrel shotgun is worth around $200 if it is fully functional, but not in like-new condition.
about $3500
as your looking down the gun, the gauge should be stamped on the left barrel back by the stock.
Stevens 12ga. /mod dhead naught
$332 i think last time i saw one thanks