Because of vastly different experiences and results, folks are pretty opinionated about their Mini 30's and their use with commie ammo.
First, my disclaimer...I don't prefer to use commie ammo, but for such a gun, it is a fair question to know if your gun will operate with steel cased ammo, especially if that's the only ammo you have available.
I have owned three different Mini 30's. Only one of them would operate reliably with steel case and Berdan primed ammo. Domestic 7.62x39 ammo is very expensive if you're not reloading, but there is another option. PPU ammo is half the price of domestic ammo, but twice the price of Wolf and similar ammo. So it's a compromise in price. If you're planning on blasting by the hundreds or thousands of rounds at the garbage dump, it's still expensive. But if you're gonna shoot it like a hunting rifle, occasionally at the range, and for a house or pickup gun, it is a great choice.
There is a feller locally that does a show on youtube with firearms.
He actually bought one of my Mini 30's that would not operate with steel cased ammo, and did some experiments to discover what would make the gun reliable with steel cased ammo. His conclusion? Other than lengthening the firing pin protrusion, there was no remedy. Heavier springs helped some, but still without 100% reliability. His results...
https://www.youtube.com/watch?v=oGlOvOv8UE0
https://www.youtube.com/watch?v=1vEOQH4LqBM
So why do some Mini 30's operate reliably and some not? Seems like stacked tolerances allow some firing pins to protrude more than others, from the factory. Those that protrude slightly more will ignite berdan primers, while those with less protrusion will not. And there's no way to know til you actually try a gun out with different ammo types.
If you're comfortable with PPU or domestic ammo only, the Mini 30 is a great choice.