There is no one single location.
Like any other product, guns are manufactured to be sold. Buyers can be private citizens, business entities, or governments.
Not many tools of any kind are made in the US any more. There are a few air nail guns that are still manufactured in the US, including the Paslode Powermaster Plus and a few Fasco models.
a factory
Raw materials, workers, bueprints.
Every corner of the globe
The Iver Johnson Company
HD Folsom or Crescent.
Gunsmiths don't make guns - they may assemble them from previously manufactured components, but they don't actually "make" guns. Factories make guns.
Manufactured goodsGuns
they are guns,flags,mailboxes, and coffee
Check the Blue Book of Gun Values
Don't listen to him! Mercury Co.