Without requiring an NFA Class II permit (for a short barreled rifle), 16 inches. That's federal law, and it does not vary between states.
In US law, there is no legal minimum for a handgun barrel- I have a Sedgely Baby Hammerless .22 Revolver with a 1 inch barrel. There IS a legal minimum (16") for rifles and shotguns (18")
16"
1.345m
16 inches
18" for shotguns
In Ohio, the legal minimum barrel length for a rifle is 16 inches. Any rifle with a barrel length shorter than that would be considered a short-barreled rifle, which is regulated under the National Firearms Act (NFA).
Federal law requires that a shotgun have a minimum barrel length of 18" and a minimum overall length of 28". Colorado law is not more restrictive.
Yes, it meets the minimum overall length requirements. Since it is a single shot there is no minimum length required for the barrel.
As long as you follow all Federal laws, any length you want.
26 inches overall with an 18 inch barrel.
It can be, depending on the action the gun uses. It can also be illegal if you cut the barrel length below the legal limit. In the US, a Title 1 rifle must have a minimum barrel length of 16 inches, and a Title I shotgun must have a minimum barrel length of 18 inches.
The legal minimum length of a non-rifled gun barrel in the united states is 7 inches.