I don't know. They seem to be referring to shot. I don't even see any mention of cartridges or reloading here. https://www.fws.gov/sites/default/f...-approved-nontoxic-shot-requirements.pdf

Another article from Cornell.law lists it as an approved shot and says nothing about hand loads being illegal.

If you could link the document where you read that only cartridges manufactured by Enron-Metal and Boss were approved that would be great. I would like to read it. That sure is confusing.