Nope I understood that.  A shotgun barrel by itself under 18" requires paperwork as class 3. 
That's funny. It's just a piece of pipe. In Canada, the receiver is the controlled part of the gun. Of course, barrel length plays a role in determining if the over all firearm is restricted or non-restricted, but a barrel by itself is not a controlled or restricted item and can be bought or sold by anyone.
I wonder how this would be classified in the US? Up here it's not restricted: 
![[Linked Image from img115.imageshack.us]](http://img115.imageshack.us/img115/9646/p10200051ff00d5ck6.jpg) 
 Don't know that I'd care to shoot it. Made for prospectors and trappers, for bear defense.
-Cam.