Janelle Cooper was happy to confirm what was suspected. As Lt. Col. Cooper was a well educated man (Bachelor of Science, 1941, Stanford and Masters in History from University of Southern California, Riverside), words and grammar meant things to him. (Not to mention Mrs. Cooper’s degree in “Letters” (Literature) from Stanford in 1942.)
Simply put, “Gunsite” is a location, not a “thing.” That is, “Gun Sight” is what we use when we shoot our firearms. Namely, “the funny bump on the end of the gun” that we focus on as we press the trigger and properly follow-through. As The American Pistol Institute (aka Gunsite) was to be the center of learning and education for all things firearms related, it needed to be described appropriately: Gunsite!
As Paul Harvey used to say, now you know “the rest of the story.”