That happened to me with shipping a air rifle from our little local UPS shop.
The manager said they weren't licensed to take in firearms or HAZMAT stuff, but the UPS hub could.
(My guess is that they don't have the proper means to store them securely)
I convinced the manager it wasn't a real firearm, and they reluctantly took it--
saving me a trip to the closest hub that's 60 miles away.
But she did tell me not to do it again.