By the mainstream description, if it has no factory refurb marks on the receiver cover, it's un-issued. I have three of them, each from a different years. I am hoping to get one from each year and each factory to complete my collection. I have a long way to go.
In reality, the above statement is as valid is used TP. There is no way you can prove each part of the SKS is a factory un-issued production part, no matter how savvy you are at collecting. I have never been to the factory to pick my rifle before it was exported. I doubt anyone else here has either.
Here is a little piece of reality for you. Anyone can order a receiver cover from the U.S. from surplus with no factory refurb issue marks on it dated, slap it on a refurb, and cry UN-ISSUED. But for the sake of discussion here and how SKS's are graded in Canada, follow the FAQ. Take it with a grain of salt.
Un-issued rifles have basic identifiers:
1. No refurb marking on the receiver cover (diamond or square)
2. Every part on the rifle has NO movement marks. (unless someone here in Canada dinked with it before it was boxed up)
3. All matching numbers. Dead giveaway it's not an un-issued is if the serial # on the stock is X'ed out and the serial # is put on it again.
4. Bayo marks on the barrel.
That's the "simple" way to check.
To be honest, even the "un-issued" ones here are not "un-issued" because the GPNS made us pin them to five and the magazine has been "modified" so technically it's no longer un-issued. But again, use the FAQ as a guide.
