I bought an sks at an auction. I researched it alittle on simonov.com. It has Norinco on the receiver and 5XXX is on the stock, mag(fixed), "charging handle", cover of bolt handle. 230 is also on the receiver. It looks like there are machining marks in the receiver-little swerls in the metal. I am wondering if this is a sino soviet? I heard most of the serial numbers of those start with a letter, and then have four or five numbers. I also heard they have a K in a circle on the barrel. Mine does not have those features. On the receiver the factory stamp is a triangle with a 13 with little trianle or (I heard the are zeros) on each side-0130. Any info would be helpful. There is also a mark on the piece that is attatched to the barrel that the gas tube pushes on to-there are some numbers on it, but I can't read them yet. Thanks for the help.