From mouth of barrel to where it meets the cylinder.
Which pistol? Most production pistols have a barrel length of 1 to 8 inches.
yes
A pistol is a single hand firearm with a short barrel.
No
125mm
Samuel Colt
Frame barrel hammer
Ridiculous
@ 125mm
From the end (where front sight is located) back to where bullet enters barrel.
No
a 1911 barrel, by itself is not illegal, except maybe in a school.....................