NO! Any interstate firearm (rifle/pistol/shotgun) shipment must go to an FFL!
A citizen can send a firearm to an FFL without any special paperwork other than ID, but some FFLs will not accept shipments from a non-FFL
Only FFLs can ship thru US mail.
Procedural question for FFLs. Does that include firearms made prior to 1898? Isn't that the cutoff for needing a 4473, background check and FFL?
CW
Firearms made prior to 1898 (and I think during) are not classified as firearms but as antiques so do not fall under that rule. You better be able to prove it though.