First of all - + 1 with the above posts by Lotsdragon
Well, if you are considering buying an SKS - In my opinion, a fine semi auto rifle - and have some... or many, questions may I suggest you go here:
Lots of knowledge and lots of fine people there willing to share it.
I've suggested there for folks to come here when they have questions to which - being that here we have experts on the particular firearm in question (e.g. Mr. Bill Goforth on the old H&R and Iver Jonson pocket revolvers) a thorough answer would be "best" found in this forum.
So here I'm giving you a site were people eat, breathe and live SKS...
I'm new here myself, so I hope this is OK with the admins here - if not please advise.