Since then, several states have passed laws banning them, and the Justice Department has said it may reverse a 2010 decision and ban them under federal law. In May, Slide Fire Solutions, the largest bump stock manufacturer, which holds a patent on the devices, closed operations. (Its inventory is still being sold online.)

For gun control advocates, this seems like a victory, and it may be — or it may not. State and local bump stock bans face legal challenges, and local ordinances banning the devices in Ohio have been overturned.

More to the point, Mr. Hardeman said that he or most anyone at the bar could rig a semiautomatic firearm to simulate an automatic fire rate in 15 minutes, no bump stock needed. Brownells continues to carry parts and accessories that achieve similar results, including binary trigger modification parts, which ship to 44 states.

Mr. Hardeman told me a familiar story. He is proud that he was able to contribute to his impoverished household in his boyhood by hunting small game. When he hears that gun owners are irresponsible, he tells me, he’s affronted. To him, his neighbors are lumping him and his friends in with a group to which they don’t belong. He said it seems impossible to talk with them. “Liberals want to take my guns,” he said.

Virtually everyone in Grinnell has taken great care to say that they do not want to take anyone’s guns. This includes Ms. Abrahamson and Ms. Scott, who says that the distinction between gun control and gun safety matters. “Many of us are gun owners,” Ms. Scott said. “We don’t want to challenge the Second Amendment. We just want to know if there’s safety where there are guns. This is not an anti-movement.”

“But it’s what I hear all the time,” Mr. Hardeman said, throwing up his hands.

Before I could ask, the bartender set another frosted mug in front of me. “No, someone else got it for you,” she said when I tried to pay.