Near the end of YG’s My Krazy Life, easily my favorite rap album of 2014, there’s a posse cut called “When I Was Gone,” and it’s a weird one. Other than YG, there’s nobody famous on that song; they’re all random Compton guys, guys you assume have known YG forever. And they aren’t rapping about how awesome they are, how they’re taking over the rap game. Instead, they’re rapping about how their girlfriends cheated on them when they were in prison, or about how those girlfriends didn’t write them enough letters. YG’s album is a sort of every-knucklehead day-in-the-life concept album, and so “When I Was Gone” functions as a sort of pull-the-camera-back moment, almost the way “Compton” did on Kendrick Lamar’s Good Kid, m.A.A.d. City. YG’s story, about partying and breaking into houses and being betrayed and spending time in prison and apologizing to his mother, is not unique. Every guy on the song has a story like that one. One of those random guys is Slim 400, a rapper signed to YG’s Pushaz Ink label. And Keepin’ It 400, Slim’s own full-length, feels broadcast from the exact same universe as My Krazy Life. As a mixtape, it exists in the current moment, a moment when West Coast rap has a sound defined by YG’s frequent collaborator DJ Mustard, but it also has deep roots within California street-rap, roots that pop up above the surface every so often. Keepin’ It 400 is what solid, durable G-rap can sound like in 2014, the present-day approximation of, say, an MC Eiht or Above The Law album. And it bangs.

Slim 400 isn’t a Chevy Woods or a Murphy Lee, a rapper entirely defined by his relationship to a more-famous benefactor. YG only shows up on one track, and DJ Mustard only contributes one beat. You never get the sense that these are rejected YG tracks that he threw to his little buddy, or that Slim and YG are in any way inseparable. But Keepin’ It 400 is a West Coast rap record in 2014, which means it exists in Mustard’s shadow in some important ways. The tracks here are clipped and spacious; the lesser-known producers here use a lot of handclaps. And Slim has a plainspoken, conversational snarl in his voice, like YG does. As a rapper, Slim’s got a more nasal voice, and his delivery is a bit more laconic. Unlike YG, he’s not that interested in letting us in, in telling the world about his day-to-day frustrations. As a lyricist, Slim is more interested in time-honored head-busting tricks; he spends much of opening track “Real Nigga Shit” describing, in loving detail, exactly how he’s going to murder you. But like YG, Slim’s greatest strength isn’t his on-paper lyrics; he doesn’t say anything particularly worth quoting. It’s how he sounds so comfortable, so completely at home, in this vicious world he describes. That’s an old gangsta-rap trick. Rather than growling and roaring and projecting outrage, he comes off calm and relaxed, like he’s thinking about fucking you up but it’s not even that big a deal to him. He sounds cool and dangerous in equal measure.

By that same token, for all its Mustard echoes, the music on Keepin’ It 400 belongs very much to a long-established rap lineage. “Real Nigga Shit” rests on a forbidding, minimal sample of Edwin Starr’s “Easin’ In,” the same song sampled on Ice-T’s “High Rollers” and DMX’s “Crime Story” and Prodigy’s “Mac 10 Handle,” and it’s great to hear those itchy congas again. “Bring Da City Out” has eerie synth tones that remind me of what DJ Muggs used to do on Cypress Hill records. “Get Money, Fuck’n Bitches” is old-school Bay Area Mobb Music, the sort of thing E-40 would’ve torn apart once upon a time. Plenty of the tracks here have synthetic slow-rolling basslines that owe everything to the tracks Ant Banks used to make for Too Short. None of it is retro-revivalist obvious, but it all seems rooted in the stuff that Slim must’ve grown up hearing. It’s one generation of workmanlike hooligan-rap learning from another, and building on what the other already did. (As for that one Mustard beat, on “Where The Party At,” it’s one of his weirdest ever, a maddening Pac-Man keyboard line worming around in your brain.)

Last week in this space, I wrote about how it can be really, really hard to find mixtapes to write about some weeks. But there was no shortage this week, and a lot of them were good. For whatever reason, rappers love to release mixtapes over holiday weekend, and the days around the 4th of July brought good sounds both expected (Lil Durk making bleakly emotive melodic Auto-Tuned drill music, Young Scooter rapping in a way that I can only describe as “agonizingly effortful”) and not so much (The-Dream cooing sweetly over a “Shook Ones, Pt. 2″ sample, Ricky Eat Acid building a weird-rave anthem out of a Slim Thug punchline). One or two of those might make it into this column in later weeks, especially if we get another barren week or two. But in a busy week for mixtapes, the one that grabbed me most immediately was the one that took a durable old sound, tweaked it enough to make it sound new, and presented me with an hour of energetic and vital rider music. Really, that’s all I’m asking for.

Download Keepin’ It 400 at Livemixtapes.