There seems to be some confusion about whether the US mail can be used to ship certain firearms, including antiques or black powder guns. I have been hoping that by now someone would have provided a detailed discussion of postal regulations on the subject, but that has not occurred yet, so I will give it a try.
First, the USPS has its own definitions regarding firearms and the mail, so definitions from ATF or other sources should not be relied on unless the USPS uses definitions from those sources.
USPS definitions can be seen here:
http://pe.usps.com/text/pub52/pub52c4_008.htm
A firearm as defined in section 431.1 is “any device, including a starter gun, which will, or is designed to, or may readily be converted to, expel a projectile by the action of an explosive….” That same paragraph has an exemption for antiques, but
note that antiques are not exempt if they meet the USPS definition of a handgun.
Section 431.2 defines handguns like this, “Pistols, revolvers, and other firearms capable of being concealed on the person (for example, short-barreled shotguns and short-barreled rifles) are defined as handguns.”
Section 431.3 defines antique firearms. Note that nothing says that an antique firearm is not a firearm. Nothing says that a black powder firearm is not a firearm. In fact the Post Office definition of antique firearms is not used for very much in other parts of the regulations.
Post Office regulations about what can be mailed are listed here:
http://pe.usps.com/text/pub52/pub52c4_009.htm
Section 432.2 says, “Handguns and other firearms capable of being concealed on the person are nonmailable unless mailed between the parties listed in this section….” The listed parties who are allowed to mail handguns are basically FFLs, licensed manufacturers, some government agents, and some museums. One unique exception is that C&R licensees can mail C&R guns between themselves if the C&R gun also meets the USPS definition of an antique. Note that the quoted language refers to mail “between” parties, which means that an acceptable party must be at both ends of the shipment.
The OP asked about mailing a Ruger black powder handgun which is basically a generic replica of a 19th century revolver. Others have commented that they have sent or received black powder guns by US mail. As I read the postal definitions and regulations, if you are not one of the allowed parties listed by the USPS, then you are prohibited from sending or receiving by US mail any handgun, regardless of how old it is and regardless of the type of powder it is designed to use. Under USPS definitions, an antique handgun is still a handgun and a black powder handgun is still a handgun, and most of us are prohibited from using the mail for any handgun.
