How is the barrel length measured on a revolver? Does it include the length of the cylinder? In the state of WI, the DNR states the barrel length is measured from the firing pin to the muzzle with the action closed (rear of cylinder to muzzle).

IIRC if the chamber is part of the barrel, than you measure from the breach face to the muzzle (IE rifles, shotguns, self loading pistols, etc). If the chamber is seperate from the barrel (IE revolvers), than it's the barrel length ONLY (IE: face of cylinder to muzzle)