The story about 'some' CBC 75 is the Brazillean Army bought a quantity of linked ball, but they had seating depth problems. So they sold the whole shipment to Chile. The bullets were pulled on all of it and the powder dumped into a hopper. Some one some how mixed in some identical looking pistol powder. The Chileans found that problem and quaranteened it all. It was sold as scrap, but boys will be boys and it ended up on the US surplus market. A full auto collector had a catastrophic blowup. There was a class action lawsuit and a recall and everyone looked for the guilty parties. If the ammo is in square cardboard boxes with an inked label from Century, it is part of the suspect loading.
There is a brighter ending than you might think. Gold Cross pulled the FMJ bullets and loaded a pretty decent run of 155gr Sierra Palma target ammo with those primed cases. I bought a case from a CGN'er but my reloader pulled the bullets and recharged with 4041. The reloads are packaged in different boxes with the recipe and dates. It shot just fine in my Norinco. So not everything about CBC is bad, just when it is left as is.