Grooves cut into the inside of a gun barrel for the purpose of spinning the bullet when fired.
Looking Down the Barrel of a Gun was created on 1989-07-25.
Threaded
broach is the tool to cut rifling.
The rifling in the barrel. These are grooves cut on the interior of the barrel that twist around and cause the bullet to spin as it passes down the barrel. The spin stabilizes the bullet and promotes accuracy.
bandsaw
A whippet gun is a Browning Auto , or a Remington model 11, cut down ( so that it still operates) Both the barrel, and Stock are shortened. See related link for more info.
Best left to a gunsmith
You look down the barrel and if it is swirled it is a rifled barrel and if it is not swirled it is a smooth bore
A shotgun is an example of a smoothbore. The inside of the barrel has no grooves cut into it, as a rifle would have.
The bore is the inside diameter of the barrel. Simply put, it's the hole down the middle of the barrel.
The Crosman 120 is a rifle not a gun. It is a break barrel. Cock the barrel all the way down and load a pellet into the rear of the barrel. Pull the barrel back up and it' is ready to fire.