On August 2, while OutKast headlined the second night of Lollapalooza in Grant Park, Bongripper capped a two-day DIY bash called Gnarfest with a free set at the Illinois Centennial Monument in Logan Square. The local instrumental doom band stood at the head of the broad steps that lead to the monument, its column at their backs. Hundreds of fans filled the stairs and lawn around and beneath them (or sat atop the monument's high marble base), nodding their heads in slow unison as Bongripper plowed through "Into Ruin," the grim, lumbering 28-­minute track that closes 2014's Miserable.

It took nearly ten years, but Bongripper have found their audience. At one of their very first shows, a 2005 punk fest at Northern Illinois University, they weren't so lucky. "It was a bunch of hardcore breakdown bands and then us," says bassist Ron Petzke. "We just had one riff, and we played it for 30 minutes. We started playing and there's like 40 or 50 kids in this cafeteria, and within ten minutes there were four people." By the end of the set, only one person was left, and he was a friend of the band. According to guitarist Dennis Pleckham, he offered them words of encouragement afterward: "There were some good parts."

When Petzke, Pleckham, drummer Dan O'Connor, and guitarist Nick Dellacroce started Bongripper, they weren't new to metal—they'd loved it since they were kids—but they didn't consider themselves part of the metal scene in Chicago. They felt more at home alongside punk and noise bands on the DIY circuit, where their friends hung out. Their tectonically heavy, mercilessly loud, and obnoxiously slow songs were undeniably metal, but they almost never shared bills with other metal acts.

Bongripper made their recorded debut in 2006 with the self-released The Great Barrier Reefer, whose single song runs almost 80 minutes. Today they still self-release their music, and they've never hired a manager or a publicist. They send no music to reviewers, not even digitally, and their promotional efforts rarely extend beyond the occasional Facebook or Twitter post.

But almost in spite of themselves, Bong­ripper occupy a prominent place in Chicago metal—and increasingly, in metal at large. Dellacroce says about 11,000 people have downloaded Miserable since the band released it as a pay-what-you-want download via Bandcamp in July (it's now $5). According to Bandcamp chief curator Andrew Jervis, Miserable was among the top-selling Chicago albums on the site last year, both in number of sales and in the total amount fans spent on it. Bongripper have sold a fair amount of vinyl too—the first pressing for Miserable was 1,000 copies, and the double LPs sold out in three days at $22 a pop.

Next month Bongripper will make their second trip to Dutch metal festival Roadburn, one of the most important events in extreme music. Now in its 20th year, the fest has booked more than 100 acts, including New Orleans sludge outfit Eyehategod, Norwegian black-metal group Enslaved, and Claudio Simonetti's version of Italian prog institution Goblin. Bongripper, far from being buried in the small print at the bottom of the lineup, are among the 15 bands that appear (in nice big letters) on the promo poster that fills the front page of the Roadburn website. They'll perform twice at the four-day fest, and at one of those shows they'll play Miserable in its entirety. Bongripper also headline Beat Kitchen on Friday, but if you don't have tickets already, good luck—the show sold out in less than a week.

Bongripper's style of doom, with its atmosphere of suffocating dread and its songs that last for weeks, can feel deliberately antagonistic. But Los Angeles-based freelance writer Jeff Treppel, who included Miserable on a list of 2014's best Bandcamp finds for metal magazine Decibel, sees past its confrontational surface. "Obviously it's all slow and dark, but they really work in some variety, and they fill the space between beats well so it never gets boring," he says. "At this point in my metal listening, I'm not expecting a band to blow me away with originality, but if they have a strong grasp of songwriting fundamentals, it carries them a long way in my book. They're just good."

O'Connor, Petzke, and Dellacroce, who are all 29, grew up together in suburban Westchester, where Petzke and Dellacroce lived across the street from each other. They started their first band, whose name they prefer not to share, shortly after O'Connor got a drum kit at the end of eighth grade. "Nick, myself, and Dan have been playing music together since we were 13, 14 years old, and we've known each other our whole lives," Petzke says.

"Our early stuff was like bad high school metal—Slayer rip-off shit and whatever," Dellacroce says. "It ended up turning more kind of like grindy tech-death metal kind of shit."

They started out practicing in Petzke's parents' basement. To this day Petzke's dad, Ron Petzke Jr., goes to almost every Bongripper show—he's even traveled to Europe to see them play. He also introduced the band to Dennis Pleckham, who's now 35. "I actually worked with a guy that had a friend who had a recording studio in his basement, who turned out to be Dennis," says the elder Petzke.

Pleckham helped O'Connor, Petzke, and Dellacroce's pre-Bongripper bands record a few demos, and in 2004, after running into the three of them at an Isis and Pelican show at Metro, he joined the last of those groups. They'd lost a guitarist, and Pleckham offered to step in. At the time, they still had a singer—a Detroit native and Columbia College student they'd rather not name. ("It's all done; it's in the past," Pleckham says.)

In 2005 that singer graduated from Columbia and moved back to Detroit. At first, the four of them continued to practice the material they'd written with him. "Then one day Dan's double kick pedal broke. I turned up my amp—I said, 'Let's play some fucking doom,'" Dellacroce says.

Thus Bongripper was born. "We probably just jammed for who knows how long," O'Connor says.

"Every practice, instead of playing songs, we just did improv doom," Dellacroce says. "Then we ended up recording an album and got a few crappy shows and played some shows that people didn't like."

At first Bongripper booked gigs wherever they could, drawing on their network of friends in punk and noise bands. "We like doing stuff outside the metal scene," Dellacroce says. "We never really affiliated with that." But though Bongripper didn't identify with metal socially, they definitely understood it aesthetically. It takes more than a casual fan to cite as an influence, as Dellacroce does, sludgy Boston doom band Grief.

The name "Bongripper" started as a joke. "We were having a conversation about how Sleep didn't fill up an entire CD with Dopesmoker," Pleckham says. "They wasted what, eight minutes? Whatever time's left over, we were joking about how much they left off. I believe Nick said, 'Yeah, let's do an 80-minute track called "Bongripper."'"

The jokes kept coming when it came time to name Bongripper's songs and albums. There's the 2007 LP Hippie Killer, the 2008 LP Hate Ashbury, and the 2011 seven-inch "Sex Tape" b/w "Snuff Film." The band's contribution to a 2013 split with UK three-piece Conan is called "Zero Talent," thanks to late-night e-mail from a disgruntled nonfan. "He was up at four o'clock in the morning, just stewing about how much he hated us and that his girlfriend had dragged him to three of our shows," Pleckham says. "He called us 'zero-talent ass­clowns.'"

"You have to take us with a grain of salt, and we certainly do," Petzke says. I've learned this myself, talking with Dellacroce and Petzke at shows over the years. Once Petzke told me about a screamo band whose drummer had eaten a whole bag of chips onstage at a festival and then stormed off, and it started us riffing on the idea of a band confrontationally eating onstage instead of playing. I offered to join Bongripper on sandwich, a joke that must've stuck with Petzke—when I showed up at Bongripper's practice space for this interview, he told me he was disappointed I didn't have a sandwich with me.

"Everything about our track record should scream that no one should listen to us," Dellacroce says.

"Somehow they do," Petzke says. "It's pretty surprising still."

When Bongripper recorded Great Barrier Reefer in 2005, they did it just for fun, with no plans to release it. Dellacroce sent the album to some friends through AIM, though, and that was enough. "Next thing I knew it was popping up online that people were sharing it to everyone," he says. "It was just kind of weird. The stuff that we did and enjoyed doing—that people liked it."

Bongripper made their vinyl debut in 2010 with a double LP called Satan Worshipping Doom—up till then, their releases had been digital only or small runs of CDs, CD-Rs, or tapes. "We put that album up online, and we sold out of it before we did the release show," Dellacroce says. (As of this writing, somebody on Discogs was trying to sell a copy from that pressing for $115.) "We ordered another pressing of it, another 200 records—we did 300 to start with. We did a Reckless release thing, and that was packed. Ever since then people have just been coming to pretty much everything we do."

Everyone in Bongripper has a full-time job, so the road-dog life isn't an option for the band. But as their popularity has grown, they've increasingly been flown out of town for weekend gigs—last year they touched down in Denver, Tampa, LA, New York, and Baltimore (specifically at Maryland Deathfest). Their first Roadburn trip was in 2012. "It was weird being at Roadburn," Dellacroce says. "The promoter that put on the fest came up to us, and after we played he's like, 'You guys sold more merch than Sleep.'"

"I'm really lucky that this has worked out this way," Petzke says. "I get to hang out with my best friends every week, play music that I really like, and now, on occasion, fly to cool places and play for people who are equally stoked about the things we're doing."

Bongripper have been courted by labels, and the possibility of signing is an "ongoing topic" according to Pleckham. (He handles the group's mail-order business, so he's probably the most motivated to strike a deal.) For now, though, Bongripper remain completely in charge of every aspect of their releases—so there's nobody to tell them, for instance, not to make a double LP with just three huge songs, so that one track would have to be split. (The monstrous "Into Ruin" covers the C and D sides of Miserable—that is, both halves of the second LP.) "When we wrote it, there was a nice part—like a cymbal catch—where we were like, 'That's where we're gonna put the record flip,'" Pleckham says.

"We thought it was a dick move, where you had to flip the record and continue on," Dellacroce says.

"We talked about, on the CD version, recording someone going 'fuck' and getting up, and you hear the sound of him hitting play—just so everyone could have that experience. But we decided against it," Petzke says. "We make poor decisions."