You call it a B-24 and a P-51 motor, the credit goes to the government who only uses that designation and the serial number. It only makes a difference to aftermarket buyers of things like Jeeps. Was it made by Willys or Ford. Solders didn't care, collectors do.
Singer .45... intriguing. The Ideal canteen in not a surprise, thousands of companies, some or them household names, have blow or injection molding plastic machines and can take on contract work when they are slow.
Of course blow or injection molding a simple plastic piece is a far cry from an M1911A1.