The provisions of N.H. Rev. Stat. § 159:3 and 4 shall not apply to marshals, sheriffs, policemen or other duly appointed peace and other law enforcement officers, or bailiffs and court officers responsible for court security; nor to the regular and ordinary transportation of pistols or revolvers as merchandise, nor to members of the armed services of the United States when on duty; nor to the national guard when on duty; nor to organizations by law authorized to purchase or receive such weapons; nor to duly authorized military or civil organizations when parading, or the members thereof when at, or going to or from, their customary places of assembly.