The movement has followers in both Europe and North America. But in the United States, the First Amendment offers the bands and their labels a protection that they don't have across the Atlantic. Many European countries have restricted neo-Nazi activities, symbols and statements since the horrors of World War II, so the recordings are traded largely on a black market there, Burghart said.
White supremacist groups hold occasional music festivals that typically draw about 200 fans, usually held on rural private land because of the difficulty of booking public venues, Burghart said. They're raucous, often violent affairs in which some of the fissures among different groups flare into "fisticuffs and scuffles," he said.
And Gletty told CNN's "The Situation Room" that the crowds "have the mindset of a pit bull."
"In one moment they're like a mother pit bull licking their little puppies, and then, 10 seconds later, they're just off the wall doing something crazy," he said. "Their mind snaps, but they love this ... the ones that commit this violence, they thrive on this, and most of them really feel that it's the government pushing them towards this."
But while the stereotype of the skinhead is a brawling, blue-collar kid, "today it's far more of a middle class or even upper class phenomenon," Burghart said.
He cites the example of Benjamin Nathaniel Smith, a young neo-Nazi who targeted blacks, Jews and Asians in a weekend of drive-by shootings in Illinois and Indiana in 1999. Police say Smith killed two people and wounded another 10 before fatally crashing a stolen minivan during a police chase.
"Ben Smith was recruited through the white power music scene," Burghart said. "He was from an upper, upper middle class family from the wealthy Chicago suburbs. He went to the most prestigious high school in Illinois. He came from a stable family and yet was attracted to the movement ... He's more of the model of the folks today than in the past."
That has changed the movement around them as well, as members set up businesses ranging from tattoo parlors to cable-installation contractors to support their activities.
"It increases the desire for a kind of professionalization in the scene," he said. "So instead of doing this simply as a passion, as true believers, they saw a business model that they could bring to the scene."