Not an C&R FFL
I am a C&R FFL and work for the Post Office. here are the rules for mailing a pistol.
11.1.2 Handguns
Pistols, revolvers, and other firearms capable of being concealed on the person (referred to as handguns) are nonmailable unless mailed between the parties listed in 11.1.3 and 11.1.5 after the filing of an affidavit or statement required by 11.1.4 and 11.1.6.
11.1.3 Authorized Persons
Subject to 11.1.4, handguns may be mailed by a licensed manufacturer of firearms, a licensed dealer of firearms, or an authorized agent of the federal government or the government of a state, territory, or district, only when addressed to a person in one of the following categories for use in the person's official duties:
a. Officers of the Army, Coast Guard, Air Force, Navy, Marine Corps, or Organized Reserve Corps.
b. Officers of the National Guard or militia of a state, territory, or district.
c. Officers of the United States or of a state, territory, or district, whose official duty is to serve warrants of arrest or commitment.
d. USPS employees authorized by the Chief Postal Inspector.
e. Officers and employees of enforcement agencies of the United States.
f. Watchmen engaged in guarding the property of the United States, a state, territory, or district.
g. Purchasing agent or other designated member of agencies employing officers and employees included in 11.1.3c. through 11.1.3e.
11.1.5 Manufacturers and Dealers
Handguns may also be mailed between licensed manufacturers of firearms and licensed dealers of firearms in customary trade shipments, or for repairing or replacing parts.
11.1.6 Certificate of Manufacturers and Dealers
A licensed manufacturer or dealer need not file the affidavit under 11.1.4, but must file with the postmaster a statement on Form 1508 signed by the mailer that he or she is a licensed manufacturer or dealer of firearms, that the parcels containing handguns (or major component parts thereof) are customary trade shipments or contain such articles for repairing or replacing parts, and that to the best of his or her knowledge or belief the addressees are licensed manufacturers or dealers of firearms.
f. Licensed manufacturer and licensed dealer mean, respectively, a manufacturer of firearms or a bona fide dealer of firearms, duly licensed by the Bureau of Alcohol, Tobacco and Firearms of the Department of the Treasury, under the Gun Control Act of 1968 (Public Law 90-618), 18 USC 921, et seq.
Now which part did you not understand.
steve