I think the best way ios to find a cooperative FFL holder. They can ship though the USPS, while commoners can not. I have heard that the other carriers require over nite shipping, which is spendy.
I simply ship with FedEx. No FFL required. Get enough insurance. No need to be forthcoming about the nature of the item. Last time I shipped I went with "antique metal artwork". There is no obligation to identify contents , unless classified as hazardous - like ammo.
It is not an explosive ; it is inert.
You can ship through a licensed dealer if paying them to be responsible for the item makes you more comfortable. I prefer to ship myself .