(a) Subject to subsections (c) and (d) of this section, the Secretary shall issue a permit within a reasonable time to a person who the Secretary finds: (1) (i) is at least 21 years old; or (ii) is a person who is a member of the armed forces of the United States, the National Guard, or the uniformed services; (2) (i) has not been convicted of a felony or of a misdemeanor for which a sentence of imprisonment for more than 1 year has been imposed; or (ii) if convicted of a crime described in item