RE: 7.62x39
My siaga 7.62x39 was the biggest most innacurate POS I have ever owned. I don't think you could hit the broad side of a barn, from inside the barn! I traded it for a marlin .22 and some paintball crap.
I did have an SKS that was fairly accurate with premium ammo. And I have seen bolt actions shoot this round very well. It's not really the cartridge but rather the sloppy guns it was designed to be used in. They were built to function, not be really accurate weapons.
Paul