Portuguese, Lthuanian, Israeli, and Austrailian are very good to my experience. You have to know your headstamps sometimes. I saw what was advertised as Nigerian 7.62x51. I normally would avoid something like that but examined it and found the headstamp was Hirtenberger (made in Austria). Being "Nigerian" it was priced low and I bopught a bunch of it. It didn't have the NATO cross, chronographed a little faster, and worked well in the 7.62 NATO semiautos without adjustment.
I think we gave the Lithuanians the machinery make their 7.62 NATO when we gave them M14s during the Clinton era. It also has the plus of being boxer primed.