Shotgun can have multiple meanings:
1 It is a type of firearm with a long barrel that fires shotgun shells. Those are primarily used for hunting.
2. Riding shotgun means to sit next to the driver of a car. For example a group of friends are going somewhere, and one yells 'I call shotgun' meaning, that they are sitting in the front with the driver, as the back is seen as the worst seats because they are smaller and less room.
The term riding shotgun likely came from stagecoaches. One person handled the reins, the other handled the shotgun, apparently because stagecoach robberies were common. In today's terminology, it means window seat, next to the driver, and no firearms are involved.
3. There is also a 'shotgun marriage' which is arranged quickly and suddenly because the female is pregnant. It is possible that in the old days, the father of a young pregnant woman would threaten the baby's father with a shotgun, saying that if he didn't marry her, that the father would kill him.
4. It is also a way of using inhalable substances, where one person inhales the smoke and then blows it into another person's mouth.
"Shotgun" means the passenger side.
I am guessing you have a model 870. It is a edition of the 870 shotgun
This is a double barrel, over/under shotgun.
If you call out shotgun it means you get the front passanger seat in the vehicle.
J.C. Higgins Model number shotgun, normally 20-12
The number 1400 refers to the Model number of your Winchester shotgun.
a shotgun
Unknown.
Improved cylinder
Go here for a good explanation - http://hunting.about.com/od/shotgun/l/aastshotgunfaqa.htm
Degree of choke
A fowling piece is a type of shotgun.