; and (2) by adding at the end the following new subsection: (b) Possession of a firearm The possession of a concealed or open carry firearm by a member of the Armed Forces subject to this chapter on a military installation, if lawful under the laws of the State in which the installation is located, is not an offense under this section. . (b) Modification of regulations Not later than 30 days after the date of the enactment of this Act, the Secretary of Defense shall amend Department of Defense Directive number 5210.56 to provide that members of the Armed Forces may possess firearms for defensive purposes on facilities and installations of the Department of Defense in a manner consistent with the laws of the State in which the facility or installation concerned is located. 4. Carrying of concealed firearms by qualified members of the Armed Forces (a) In general Chapter 44 of title 18, United States Code, is amended by inserting after section 926C the following: 926D. Carrying of concealed firearms by qualified members of the Armed Forces (a) Definitions As used in this section— (1) the term firearm — (A) except as provided in this paragraph, has the same meaning as in section 921; (B) includes ammunition not expressly prohibited by Federal law or subject to the provisions of the National Firearms Act; and (C) does not include— (i) any machinegun (as defined in section 5845 of the National Firearms Act); (ii) any firearm silencer; or (iii) any destructive device; and (2) the term qualified member of the Armed Forces means an individual who— (A) is a member of the Armed Forces on active duty status, as defined in section 101(d)(1) of title 10; (B) is not the subject of disciplinary action under the Uniform Code of Military Justice; (C) is not under the influence of alcohol or another intoxicating or hallucinatory drug or substance