Answer about National Slug Rejector:
Got an email asking about the contractor. National Slug Rejector was a company that made mechanical vending machine internals. Youngsters probably do not remember Mechanical Vending Machines, as everything today is based upon computer chips and electricity.
The problem with an old time vending machine is individuals would attempt to use phony coins or slugs. National Slug Rejector had mechanical systems that were sold to vending machine manufacturers that would reject slugs, hardware washers, and non-coin circular stampings. There were a variety of methods, like checking for holes, magnetic attaction of the insert, and many other ways beyond my knowledge.
This contract for Rifle Screwdrivers ran from Oct 43 thru April 44.