Around 10 years ago, I bought a thousand rounds of 7.65 Argentine/Belgian Mauser ammo. It was headstamped FN 32 or 33. Every bit fired without a hitch.
On the other hand, I bought some Argentine .45 auto which was from the 50s. It was clean and bright but was about 90% bad. It had obviously been stored badly, probably over heated.
There is, apparently, some super horrid Argentine 7.62X51 that still surfaces occasionally. Whatever is in it goes off with ~130K PSI chamber pressure, guaranteed to roach a gun...