Saco manufactured an M60 that was destroyed and sold as scrap. After that Saco M60 was demilled/scrapped, it was no longer a machine gun, it's just scrap metal. There is no manufacturer for a piece of scrap metal. The form 4 should show the maker/manufacturer as JW Law, as he is the one who made it a machine gun on a form 2. Not to say that aren't many improperly registered MGs out there..
Every HK sear host/receiver MG I've transferred that had HK or Germany on the paper form 4, came back with Vollmer, Fleming, etc. Just as every FNC came back S&H instead of Belgium.
YMMV, as this NFFA world is anything but consistent.