Surplus and most commercial 7.62 is produced for the AK's and SKS's. They are notorious for slam-fires due to protruding firing pins.
That's a little harsh. I have two SKSs and my friends have some too. We've fired many thousands of rounds thru our rifles without a single problem. I've never personally heard of anybody having a slamfire in their SKS.
I have heard ONE internet story about a guy who's buddy had a slamfire, lost control of the rifle, which bounced around while firing full auto and ended up shooting the guy in the head. I don't know if that story is true or not. I'd bet real money that the guy failed to properly clean the old crusty gunk out of the surplus rifle before he fired it. There are several versions of this same story floating around, however I find it very hard to believe that multiple people have lost control of their rifles and gotten shot in the head like that. I call BS. It's propaganda from commie SKS haters who can't stand the fact that SKS are so darn reliable AND inexpensive, plus rangemasters can't reload the surplus ammo casings.
IF such accidents happen, they're likely the gun owner's fault for not cleaning it properly. Especially an old rifle. One local range prohibits loading more than 2 rounds in SKS rifles at one time. Silly!