This is such a long shot that its probably ridiculous, but here goes. Back when Arlington Ordnance was importing M1 rifles and carbines from Korea I read that only those firearms that were sold or given to Korea could be bought by Arlington. If the guns were loaned to Korea, then they still belonged to the USA. It was a problem. If the exporter thought that the TSMGs were loaned, and that if they were worried that Uncle Sam kept track of the serial numbers, then they might have changed serial numbers, to avoid the lend lease problem. Hey, I told you it was a long shot. Jim C