cdoc42, Advertised revolver barrel lengths are often nominal, but in any case easiest measured from muzzle to front of cylinder. That measurement will be a few thousandths different than measuring muzzle to face of forcing cone due to B/C gap, if it matters. Your 5 13/16", would be shown in the catalog as a 6" inch barrel. Just as a similar for instance, I have a Colt revolver with a "4 inch barrel" that is actually only about 3 7/8". More recently, manufacturers seem to be starting to advertise barrel lengths closer to actual length,e.g., S&W revolvers with 1 7/8" barrels instead of "2"" barrels. Odd, but more correct. I wouldn't be surprised if owner/s somewhere had sued over being shorted 1/8" of barrel or something...