I don't believe that my Norinco is, now I'll have to dig it out to check.
Mine does not... that looks like machining [STRIKE]error[/STRIKE] art.
Mine does not... that looks like a machining error.
Mine don't. Curious where that came from.
[0136] arsenal mark, CJA SHFD MI importer mark, serial number starts with 23.
I did some searching around Youperj's SKS web site. The checkering on the base of the bayonet is basically universal, but I didn't see any with ribbing on the barrel.
Did find a couple of other mentions of "ribbed" or "radiator" barrels. Here is one thread. It is definitely unusual.