Reloading equipment has no daft U.S. exporting rules. Components do, but not the kit.
"...dealt with the company..." Yep and long before there was such a thing as e-mail. One letter asking where I could get some decapping pins got me a package of 'em and a list of retailers. As mentioned, a phone call(you talk to a person right away too) or e-mail will do it now. And RCBS' warrantee is on the equipment, not who bought it new. So if you buy used kit you're still covered, no questions, other than your mailing address, asked.
I think, but I'm not sure, that Lyman has a limited warrantee. As in it's not as good as RCBS'. Of course, you don't pay the kind of money for Lyman kit that RCBS wants either.