18 inches. Anything shorter than that requires a Class II NFA permit for a short-barreled shotgun. Doesn't matter what state you're in - that's federal law.
18"
There is no restriction on barrel length but the overall length of the firearm must be 26.5 in or greater
That would depend on the make and model of the shotgun in question,and the length of the barrel/barrels that came with the shotgun.
1.345m
18" for shotguns
If you mean the legal length of the barrel? it is 18 inches and for rifles it is 16 inches.
As long as you don't violate BATFE regulations on overall length (26" or longer) and barrel length (minimum 18"). Your barrel has to be over 18" long! I have shortened several, and make them at least 18 1/2" from the closed bolt, usually longer. Otherwise you are committing a federal felony.
26 inches overall with an 18 inch barrel.
Unable to answer as asked. Is it already a shotgun or will it be built from a virgin receiver?
No. Barrel must be at least 18" and overall length no less than 26"
The legal minimum length of a non-rifled gun barrel in the united states is 7 inches.
According to federal law the shortest barrel length allowed for both rifle or shotgun is 16 inches.