If the barrel is No.4 original contour with no markings of any sort and the bayonet lugs, there is a good chance it is a Canadianicon made barrel. I did a photo essay of the different types of barrels here some time ago and will see if I can find the photo used. The Canadian DCRA barrels did not have a bayonet lug but will be marked with 7.62 and the C with A on the muzzle. The barrels with the bayonet lugs in the white as the originally surfaced out of CA have No markings. There was also another Canadian barrel with a much heavier profile but as I have only ever seen the one I have, I don't think it was a production run. I'll have to check it as the heavy barrel has surfaced during a major clean up and finding all sorts of kit that I never knew I had....