49 CFR § 1540.111 - Carriage of weapons, explosives, and incendiaries by individuals.
(a) On an individual's person or accessible property - prohibitions. Except as provided in paragraph (b) of this section, an individual may not have a weapon, explosive, or incendiary, on or about the individual's person or accessible property -
(1) When performance has begun of the inspection of the individual's person or accessible property before entering a sterile area, or before boarding an aircraft for which screening is conducted under this subchapter;
(b) On an individual's person or accessible property - permitted carriage of a weapon. Paragraph (a) of this section does not apply as to carriage of firearms and other weapons if the individual is one of the following:
(1) Law enforcement personnel required to carry a firearm or other weapons while in the performance of law enforcement duty at the airport.
(1) Any loaded firearm(s).
(2) Any unloaded firearm(s) unless -
(ii) The firearm is unloaded;
(iii) The firearm is carried in a hard-sided container; and
(iv) The container in which it is carried is locked, and only the passenger retains the key or combination.
(3) Any unauthorized explosive or incendiary.
(d) Ammunition. This section does not prohibit the carriage of ammunition in checked baggage or in the same container as a firearm. Title 49 CFR part 175 provides additional requirements governing carriage of ammunition on aircraft.