Mini 30's like brass cased ammo, not steel cased surplus. You will get a failure to fire about once in 20 rounds with Wolf, Tula, any of the imported stuff. The primers are harder on the steel cased ammo, and the Mini 30 likes the softer primers found in brass cased ammo.
I have a newer (two years old) Mini 30 that I will shoot cheap steel cased ammo when plinking, when reliability is important or accuracy is desired, I use PPU soft points, cost about $10 for a box of 20. I also have good results with Fiocchi, Winchester white box, Federal and Remington soft points. None are as accurate as the PPU soft points though...