Most of this type surplus ammo goes into surplus battle rifles who's chambers could very well be slightly worn but not in need of replacement. Most T+E gages are not a go and no go gage but a measuring device to show wear. These types of chambers do not merit replacement just because they are not new. They do need reliable ammo capable of expanding to the chamber dimensions, not brittle, corroded, out of speck rounds.
From the looks of the picture posted, I'ld say this is Yugo made ammo that may have been in the country of Venezuela for a while, before it was imported here.
What type of firearm will you be firing this ammo in, can you post pics of your ammo that has the corrosion instead of the informational sales pic.