Re the stepped muzzle: Laidler believes they were likely re-worded mk3 barrels or in some cases reworked mkV. A measurement of the step will tell which it is. But at any rate the barrel will be British, since we did not make either of those barrels. If you remove the barrel nut from the barrel, the markings are often seen underneath, especially if it were a Cdn barrel . I would be very surprised to learn of a stepped barrel that is Cdn made. We did have some mk3 guns remain in Cdn servie into the 60s, although the numbers represented from the cutups I observed were quite small. I think it doubtful that Canada would have bothered to produce the barrels for the small amount of guns in peacetime.
When you say "not the prettiest welding", what do you mean? By the time of the Chinese scripted guns (actually, somewhere around the 2L to 3L guns), thee magwells should be smooth finish, the trigger housings and rear sight ring area were all spot welded to the tube. The only ugly weld was usually the front sight, which would have a small weld on the front to prevent it from wandering. Even that would usually be dressed up somewhat so the finger guard would fit on OK.
