From the breech.
From the breech
There is no restriction on barrel length but the overall length of the firearm must be 26.5 in or greater
18"
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.
A shotgun barrel length or rifle barrel length starts at the point where the rim of the case touches the shoulder of the chamber and extends to the tip of the muzzle. In most cases, if the barrel is threaded on, yes it would include the threads. lcj
If you mean the legal length of the barrel? it is 18 inches and for rifles it is 16 inches.
A little over 36"
@ 40" or so depending on LOP and Barrel length.
long
1.345m
18" for shotguns