RE: sks
It shoots the russion round 7.62 X 39. It is a fund rifle for plinking and a pretty foolproof system.
You will need to obtain some directions about dissassembly abd re-assembly along with some cleaning tips, but the procedures are not all that complicated.
Ammo can be failry inexpensive, but if you get into the corrosive stuff just make sure you clean it up well when you go to put it away.
I've got 3 of 'em , and they are fun at the range. I put scopes on 2 of them.