Looks like a South American early to mid 1600s 8 reale cob. I do not see the AC you are talking about on the shield side.
That is called the Hapsburg shield. Prior would be the script of Charles and Joanna, and after the Shield cob would be the Pillars and waves instead of the shield. I am no expert, hard to say from a small picture. Looks to be corroded or maybe positive relief where it should not have positive relief. Bumps where it should be smooth. Which could be from molding off a coin and casting a fake one. Bubbles in the plaster of the moldMaybe take some side pictures, of the edge, and maybe close ups of the cross side and the shield side.