No person shall discharge any firearms, air guns, spring guns, sling shot or other instrument or weapon within the city except in self-defense or in the discharge of official duty or during a memorial service or veterans' funeral or at an indoor rifle range operated under the supervision, guidance and instruction of a duly commissioned officer of the armed forces, including the National Guard and reserve forces, or a duly qualified adult citizen of the United States who has been granted a certificate as an instructor of small arms practice issued by one of the armed forces of the United States, the Adjutant General of the state or by the National Rifle Association of America.