Firearms manufactured prior to 1898 do not require a dealer transfer. That's the only exception for a firearm that fires a shell or cartridge. Black Powder firearms also do not require a dealer transfer, no matter the date of manufacture.
I do believe that a modern ammunition centerfire or rimfire no matter the year, smokeless or black powder needs a FFL or C&R license.
Try shipping a black powder Colt SAA made before 1898 or a centerfire long gun without going thru a FFL or C&R and you will be going to the cross bar hotel.

An original 1866 44 RIMFIRE Winchester can be received without FFL but an original centerfire 1873 can not because the 44 rimfire ammunition is not readily available.
For example when you remove the percussion cap cylinder can these Old Armys be received with the conversion cylinder in them and no FFL??? The Ruger states the gun is Black Powder Only, the cartridge is Black Powder.
NO THEY CAN NOT the key word is type of ignition not Black Powder or Year.
(16) The term "antique firearm" means— (A) any firearm (including any firearm with a matchlock, flintlock, percussion cap, or similar type of ignition system) manufactured in or before 1898; or (B) any replica of any firearm described in subparagraph (A) if such replica— (i) is not designed or redesigned for using rimfire or conventional centerfire fixed ammunition, or (ii) uses rimfire or conventional centerfire fixed ammunition which is no longer manufactured in the United States and which is not readily available in the ordinary channels of commercial trade; or (C) any muzzle loading rifle, muzzle loading shotgun, or muzzle loading pistol, which is designed to use black powder, or a black powder substitute, and which cannot use fixed ammunition. For purposes of this subparagraph, the term "antique firearm" shall not include any weapon which incorporates a firearm frame or receiver, any firearm which is converted into a muzzle loading weapon, or any muzzle loading weapon which can be readily converted to fire fixed ammunition by replacing the barrel, bolt, breechblock, or any combination thereof.