The organizers of New Zealand’s largest gun show say they have canceled the event to show respect for victims of the Christchurch massacre and because of “elevated security risks.” New Zealand Prime Minister Jacinda Ardern vowed to tighten gun laws after the attack. She says banning private ownership of semi-automatic rifles, which were used to devastating effect in the attack Friday on two Christchurch mosques, is an option. The Kumeu Militaria Show, near Auckland, has been held for about five years. …