From afar, it may seem ShrapKnel is a new name in the East Coast underground. But the duo of PremRock and Curly Castro released their self-titled debut in 2020 on Backwoodz Studioz, the New York rap label founded by underground patriarch billy woods.

Two more releases on the label followed, before ShrapKnel doubled their catalog in a span of weeks this summer with the releases of three new albums: "Armature," "Salsir le feu" and "Lincoln Continental Breakfast." This triple venture for the artists, who each have a connection to the Philadelphia region, is collectively dubbed the "Triple Steel Beam Collection" and has been a second wind for PremRock, 40, and Curly Castro, 48, the yin and yang voices that combine to make ShrapKnel.

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Each has his own discography stretching back to the early 2010s, when underground rap was ruled by a few fast-moving blogs and CD sales were still a means to a liveable wage.

Castro, whose real name is Kinte McDaniel, thrives as an enigma, channeling the snarl of Ol' Dirty Bastard. Conversely, PremRock raps with the precision of a sniper rifle, an immense calm to Castro's rousing hurricane. As individual acts and together as ShrapKnel, Castro and PremRock have built a defining catalog of modern East Coast underground rap.

PremRock, aka Mark Debuque, was born in Philadelphia and Curly Castro in New York, before each made the jump to the opposite city. PremRock was raised in Quakertown, Bucks County. Castro is a born and raised Brooklynite who went to Temple University and has stayed in Philadelphia ever since.

Castro cut his teeth on campus shows and opened for the likes of Brand Nubian, G. Dep, and Nas & Kelis. A push to perform more in New York led Castro deeper into the underground, where there were far more "really high-end, talented hip-hop shows," he said.

Provided image/Fused Arrow Records

ShrapKnel, the underground rap duo comprised of Curly Castro, left, and PremRock, released three albums this summer, collectively known as 'Triple Steel Beam Collection.'

"Castro routinely used to do multiple shows a night in Philly, sometimes for 1 verse, sometimes being a hype man, sometimes doing an entire solo set. He was constantly moving around town," Zilla Rocca, another rapper in the city, said recently via email. Rocca and Castro formed the Wrecking Crew clique with producer Small Professor.

Stuck in the suburbs, PremRock's early exposure to hip-hop was during the tape-centric heyday of rappers like Eazy-E, Wu-Tang, and later Bone Thugs-N-Harmony. Gold-standard rap publications of the time, like The Source and Blaze Magazine, became crucial arbiters of hot-or-not. The early internet age then provided him easier access from Quakertown to the world of indie rap, which was then defined by labels like Definitive Jux and radio shows like "The Stretch Armstrong and Bobbito Show" on Columbia University's WKCR.

PremRock's life in New York mashed grueling daytime jobs and late-night, open-mic appearances on any stage that would have him perform, including legendary spots like the Nuyorican Poets Cafe and the Sin Sin Lounge. "I became obsessive with finding out what place to go" PremRock said during a zoom call. "There'd be times where I'd get there, put my name down, and I would never get up".

"I've been through that," Castro said.

"That's called paying dues," Premrock responded.

The seed for ShrapKnel was planted back in 2011 at the circus. Curly Castro and PremRock met at "Rhyme Calsthenics," a traveling rap game show out of Pittsburgh. Castro was competing in the show as part of Wrecking Crew.  PremRock, also friendly with Zilla Rocca, was roped in as a last-minute replacement for one of the group's members.

PremRock recalled being warned, "Castro's gonna wash you. And I was like, 'Who the f---? Nobody's gonna wash me.'"

Even though he was in New York, PremRock joined the Wrecking Crew. The group allowed individual artists to attack the Philadelphia underground with a strong support system by their side. "We wanted strength in numbers, because the Philly scene flips every year. New cats, new promoters, new venues" Castro said. "You want to stay consistent and keep driving that spear."

The group made a splash with tapes like "Wu-Tang Pulp" in 2012 and "Thieves with Good Taste" a year later.

"Me and Zilla had a mission statement: It was important to develop catalog." Castro said. "We came from a downloads-heavy era and didn't have physicals. Digital was fine to get started, but if you want a fan base, you have to put out physical products."

That turned up the pressure to achieve a higher level of quality, which improved their pens and pushed them to release better material with better bars and better performances year-on-year.

"I always tell the guys, and they know this. They hate hearing it all the time, but man sharpens man like steel sharpens steel," Castro said.

A steady stream of work into the late 2010s built their reputation even as the scenery of underground rap on the East Coast changed. The demise of blog culture eliminated a part of the ecosystem where PremRock and Curly Castro had launched their careers, as did the decline of downloads and CD sales.

As once-headlining names in the underground scene, like El-P and Aesop Rock, retreated into various corners of the wider hip-hop stratosphere, dedicants like billy woods continued to build infrastructure around their communities and craft. The debut of ShrapKnel in 2020 felt like the perfectly timed culmination of a decade of labor, even if the group's early days were wrecked by the pandemic. The duo's records were well received online, possibly thanks to the extended attention spans afforded by stay-at-home orders. Now, with multiple albums of high quality raps and beats into their lifespan, they've put forward a compelling argument as the best Philadelphia rap group export since The Roots.

Provided image/Fused Arrow Records

PremRock, left, grew up in Bucks County and Curly Castro was born in Brooklyn but has lived in Philadelphia since attending Temple University.

"It's a story about consistency winning over perfection," Zilla Rocca said. "All of us for years were making songs, putting out projects, doing shows and runs of dates, but we didn't know what the hell would happen. Now, ShrapKnel has confidence their work together or solo is going to hit with people. That's a huge weight off your shoulders."

Fused Arrow Records is the label behind the trilogy "Triple Steel Beam Collection," and its owner, steel tipped dove, said Shrapknel is focused on a goal, "... without any sort of ulterior motives like clout or whatever. They just want to make good music and share it with people who want to hear it, and slowly but surely they are expanding that!"

PremRock and Curly Castro are rapping to the largest crowds in their artistic careers, but balancing rigorous cycle of recording and touring with keeping their personal lives afloat has remained as laborious as ever. Both work other jobs to cushion their artistry, a commonality among independent artists for whom traditionally lucrative avenues like physical sales and touring have only gotten progressively less feasible. While Castro solely works in music now, he worked for years in social services. And PremRock currently works as a bartender, with many years spent in the Manhattan service industry.

"So we'll keep pushing and finding ways to thrive," PremRock said, "even though it's getting harder."

He recalled a conversation with a fan ShrapKnel's merch table; he was asked how long before he could see the results of his hard work. " ... And I said at least 10 years. Not the answer he wanted. There's no shortcut," PremRock said.

"The work is working, but you have to stick with it," Castro added. "You can get on and off the train, but every time you come back, you're a brand new artist. Consistent people are fickle. If you love making music, keep doing it, whether people catch on or not. If instant gratification isn't your motivation, the endeavor will reward you."

PremRock said, "There's no backup plan for the music thing. I'm just gonna make music for the rest of my life until I'm dead."

"As long as I can breathe and utter guttural sounds, I will always rap," Castro said. "It's that important to me."