On the afternoon of Friday, March 13, 2020, when Michael Cargill arrived at his gun shop in a strip mall on the southern fringe of Austin, he thought he’d been robbed. The glass display cases were empty; there were no rifles hanging on the wall, no pistols secured behind the counter.

He’d been away from the store for a day and a half, and in that time every gun in stock had been purchased. “Old guns, used guns, didn’t matter whether we had ammunition for it or not,” Cargill told me. Early that morning, the City of Austin had…