WEBSTER, Texas — President Donald Trump promised to revive manufacturing in the United States, but there's one once-burgeoning sector poised to shrink under his watch: the gun industry.Fears of government limits on guns — some real, some perceived — led to a surge in demand during President Barack Obama's tenure and manufacturers leapt to keep up. Over the decade ending in 2015, the number of U.S. companies licensed to make firearms jumped a whopping 362 percent. But sales are down and the bubble appears to be bursting with a staunch advocate for gun rights in the White House and Republicans ruling Congress."The trends really almost since Election Day or election night have been that gun sales have slacked off," said Robert Spitzer, political science department chairman at State University of New York at Cortland.