Norinco: An SKS is not a 'Norinco', per se. Norinco was/is an importer. They stamped all kinds of SKS's post ban. Pre and post '66, type-D's, etc.
Chinese Type 56: I could write a book on types, factories, vairants and so on. What do you want to know? Most valuble to collectors? The lousiest one ever made- the all Stamped model (Type 63). Very rare, even more rare than the Sino/Soviet. Find a Stamped or Sino and you gotta keeper. Same with Russian/Chineese Gaurd and so on.... Chromed bore means doodly-squat. nice to look at...good luck proving it helps. Can even be a hinderance if it flakes!
Yugo: M-59, or M-59/66. These were very well made, heavy-lugged, threaded barrel, milled reciever. Good luck dating one w/o a log. Some were recond at the factory and had log books. Those are very collecable. The Yugo qualifies for C/R as they are impossible to date. The /66 is considered a Destructive Device in Ca. and must be registered.
Russians: Tula or Ish?
Romo: eh- heard good and bad, uber rare.....but collectable if 'unfired'. Good luck with that.
Blah, blah, blah..... wanna know about SKS's?
Slamfire's: Remove the bolt, tear it down, clean and reintsall DRY.
NEVER, EVER OIL AN SKS BOLT OR PIN. EVER.
Otherwise, if you don't know the diff, buy one and enjoy the cheap ammo and good shootin'.
It aint match grade, aint supposed to be, but it does exactly what it's supposed to.
Here's my Yugo. I love this gun and am very careful with it- it's in just the right state of patina.....we call her 'Ugly Betty'.
Yugo M-59, as issued, unreconditioned, 100% all there and matching numbers- complete with corroded and pitted dark bore, checked piston and all that goes with. I see some snickers and sneers when I pull her outta the bag, untill.....she clang's the 16" gongs' off-hand at Angeles Ranges at 200y, 300y, and 400y (RM shooting at 400y, my eye's suck now).