KISSIMMEE, Fla. — Don’t Be a Sitting Duck is in the business of teaching Floridians how to safely carry a concealed handgun. The Kissimmee firearms academy offers a four-hour training session required by state law to carry a loaded gun in public. For owner and firearms instructor Bryan Villella, that just makes sense. “It is our right to be able to protect ourselves,” Villella said. “To require a level of education surrounding that, I don’t see as a bad thing.” But what Villella considers a reasonable safeguard, gun rights advocate Luis Valdes sees as a government burden on the Second Amendmen...