So a huge question I am not having much luck with is this: I seeking information on whether spent shotgun shells would fall into the category of scrap metal or scrap plastic or some other kind of mixed scrap category for importing into the USA from Canada. naturally the shells are more hdpe plastic than the brass or steel casings... but how would the usa border control tag them? also would this material fall under the NAFTA compact and be consider duty free? hopefully i dont run into any hazard issues considering they are spent "used" and nothing is live including primers. the shells themselves were mostly imported from us ammunition makers, spent and now i wish to bring them for recycling of there hdpe content and of course the small amount of brass or steel. the loads would one per month consisting of 40,000 lbs packed into gaylord boxes. do i need to be certified to import this kind of material? bonded or offer sureties? how long would these loads be held at customs? any carrier suggestions who have experience importing scrap material into the USA from Canada?

Any helpful information would be greatly appreciated