I have a variant of the AK, as well as an SKS. In the thousands of personally-fired rounds, they have all been steel-cased, Eastern Bloc ammo. No failures. These guns are made for that ammo. I've also never heard of them having issues with the ammo that was designed for them, and I know a lot of guys that shoot them regularly. One thing to keep in mind is some ranges might not allow that ammo, as most of it also has bullets with steel in them.