Presumptive Republican presidential nominee Donald Trump locked, loaded and fired away at Hillary Clinton on Friday at the National Rifle Association's annual gathering in Louisville, Ky. Trump, who seemed surprised to receive the major gun lobby's endorsement minutes before he took the stage, spent most of his speech blasting the Democratic front-runner's aggressive push for gun control and accusing her of wanting to leave Americans "defenseless." "Hillary wants to disarm vulnerable Americans in high-crime neighborhoods. Whether it's a young, single mom in Florida or a grandmother in Ohio, Hillary wants them to be defenseless," the billionaire told thousands of gun...