That's quite a fleet!
I have the impression that one of the last places in the country where large gun barrels can be manufactured is in the Capital District of NY.
http://en.wikipedia.org/wiki/Watervliet_Arsenal
A couple of years ago, there were a whole bunch of flatcars loaded with tanks sitting in the small yard that is adjacent to the Port of Albany. At the time I guessed that they were coming from the armory after being serviced.