They are used quite a bit up here by our First Nations Sustenance Hunters. They were dirt cheap ( bought one for $75) and ammo was plentiful and cheap so many people bought SKS's, First Nations and everyone else. Rumours are there are more than 1,000,000 in Canada. At one time I owned 7 of them. They are good out to 100 yards, if you practise with them. Most of the ones I had, I could hit a 4-5" circle at 100 yards freehand. I now just have the CZ in 7.62x39..... our government is getting ready to ban them like they have done to all of our other Semi-automatics. A good Russian, numbers matching SKS's now fetch $800+ For ammo, if you don't reload, try the Hornady Black.
Man you got lucky. Most of the ones I've had can group 4-5 inches off the bench haha. Anyone who can consistently and repeatedly shoot a 4" target at 100 yards with an SKS offhand not only has an amazing SKS but they are in the like top 2% elite tier of shooters. I'd be amazed to see this demonstrated.