I call their main number and select sales, always seem to get the same girl, she seems knowledgeable and has gone through most of the catalog with me in the past, confirming country of origin, my geneal feel from talking to her is that most cmc branded zinc cast and bent wire are USA and all solid brass and Waterbury style are imports, that has not been confirmed, just every item I enquirer about followed those norms.
Also when I called their distributor numbers they were clueless. Their manufacturing facility is in ct, and when you can the main number you are at least talking to someone who has the ability to literally walk down to the production line and ask, their warehouses in Seattle and Cali are just distribution points.
Also the 3 digit numerical designation appears to be used on all the bent wire hardware they sell, z des on their zinc