From what I can tell, the company name is Vultee Aircraft, not Aviation.
now how about this.... via wikipedia (take it or leave it) "The first aircraft flew in September 1939 piloted by Vance Breese,[1] and was assigned registration number NX21755" Notice the last 4 digits of the serial number compared to the rifle?
Maybe it was a cheap retirement gift on 1/7/55 for the guy that nobody really liked!