Glenn - pretty easy. When Federal first started expanding their line from .22s, etc., into all the pistol calibers, some of the first ammo they sold in calibers like .25, 32, 380 and 9mm were not made by them, but rather by Hirtenberg in Austria and by Geco in Germany.
Later, I will add to this with the scan of a few box back labels showing the country of origin, and perhaps some headstamps of the ammo in the boxes, which look pretty ordinary like “FC” headstamps do.
The “FC” made in Mexico, likely actually by Industrias Technos (Aguila brand when sold commercially), are a different format, but sometimes hard to tell from Federal military or police contract ammo.
The Yugoslav version was made by Pivi Partizan, reportedly for Mexico and only on 9mm Para ammunition, but the box label is in English. It was never sold that way in the United States though, so the story may be true that it was for Mexico. It is the same headstamp style as the Mexican “FC” stuff.
Hope this helps, and it probably will more so when I get the boxes scanned and Joe gets them posted to the thread. Probably not until tomorrow some time.