I went through this with UPS a decade or so ago pertaining to AIR PISTOLS. One "Lady" in South Portland Maine refused to ship it unless I was an FFL dealer. "A handgun is a handgun", or so I was told in a very blunt manner. The "gun" was a 1930's vintage Benjamin air pistol I was trying to send out for a new valve. I tried to explain the GCA of 68 to her and the definition of a firearm, to no avail.
After writing to several higher ups in Corporate and threatening to get an NRA boycott started, they fixed the issue... REAL QUICK. She was VERY tight lipped when I returned and would not make eye contact as she accepted my air pistol.