[bluesea112]

Luke, the term "sawed off" shotgun generally means that the barrel is too short, or the overall length is too short. You could have a factory 20 inch barrel on a shotgun but saw off the stock behind the trigger gaurd and make it a "sawed off" shotgun.
It is NOT illegal to saw off your barrel. As long as the barrel is not cut shorter than 18", then you are perfectly legal.
.410 shotguns are the exception to this rule. Since a .410 is a caliber and NOT a gauge, it is technically NOT a shotgun. This is the reason it is perfectly legal to manufacture, purchase, and use a .410 handgun. A buddy of mine has a double barrel .410 handgun that is only 6 1/2" long. That thing is sweet. If you load that thing with buckshot, you are standing behind some incredible stopping power!