Even less politically active students in Virginia’s 10th Congressional District have learned Ms. Comstock’s name. “They know who she is,” said Paige Thimmesch, 16, Ms. Banks’s classmate in Sterling, Va., who is hoping to arrange the forum with the congresswoman. “They don’t know every single policy. They do know that she is pro-gun.”

Looking to history, fledgling activists are researching Vietnam-era student protests for context and inspiration. They are using words like “intersectional.” They are quoting favored lyrics from “Hamilton”: “This is not a moment, it’s the movement.”

That movement, though, will hinge on reversing years of below-average voter turnout among young Americans — translating sound and fury into the long, slow work of lasting change.

In the 2014 midterm elections, less than 20 percent of voters between the ages of 18 and 29 turned out to cast ballots, compared to more than 40 percent of voters between 45 and 59, according to an analysis of survey data by the United States Elections Project, which is run by Michael P. McDonald, an associate professor of political science at the University of Florida. Recent polling suggests the gap could close, at least somewhat, this fall. A Quinnipiac University survey released in late February found that 54 percent of those 18 to 34 said they were more motivated than usual to vote, outpacing every other age group.

While youth-driven movements in recent years, like Black Lives Matter and Occupy Wall Street, have installed themselves as forces in Democratic politics and the national discourse, their effects at the ballot box have been uncertain.

Gun owners, mindful that flurries of mass activism have often dissipated on their own after past shootings, are still taking no chances. Some efforts have been unsavory: Survivors of the Parkland, Fla., massacre in February have been the subject of internet conspiracy theories and bizarre fictions. More civic-minded supporters of gun rights are discussing counter-rallies this month to demonstrate their collective might.

“All these calls for gun control are only making gun owners snap to attention,” said Philip Van Cleave, the leader of the Virginia Citizens Defense League, a gun rights group. “This is not a one-way movement by any means.”