A MACHINE gun mailed with the United States Postal Service has been missing for weeks – and the sender fears it could be used in a shooting.Firearms dealer Steve Thompson opted for top security mail service when he sent the Israeli nine millimeter Uzi sub-machine gun in February, but it still disappeared just days later.He shipped it from Portage, Ohio, where his business Adco Firearms is based to a buyer in Florida on February 4.USPS tracking information shows it was moved to Pontiac, Michigan before arriving at a facility in Detroit on February 6, NBC affiliate WDIV reported.There, the package...