MANY shops made the SKS in China - it was practically a cottage industry! We are still finding previously unknown manufacturers' codes, and they are added to Yooper John's chart. The dating by serial # range method for the SKS in China works for the /26\ factory, but will NOT necessarily work for other factories. From what I have read, the /26\ factory was the primary PRC arsenal for production, which is why we see so many compared to others.
Norinco was a late-comer to SKS production. Most of their guns were made for the commercial market. True military contract SKS rifles usually bring a higher value.
PROUD TEA PARTY EXTREMIST!