After the high-concept gloss of their terrific JG Ballard adaptation, High-Rise, film-making partners-in-crime Ben Wheatley and Amy Jump go back to their grungy roots with a very different vision of the dystopian 1970s. In a deserted Boston warehouse, a gaggle of variously incompetent weapons buyers and sellers take random real-time potshots at each other after a volatile arms deal falls apart. Less an extended riff on the final standoff from Reservoir Dogs than an absurdist expansion of the close-range gunfight from The Naked Gun 2½, Free Fire is a delirious descent into choreographed chaos. As an exercise in stripping away narrative in favour of “pure cinema” sensation, it’s breathtakingly bold; the ne plus ultra of nihilistic screen showdowns. In terms of slapstick comedy it combines a silent movie visual sensibility with a Looney Tunes symphony of cacophonous ricochets and recoils – “Ba-Ding-Dang-BONG!”

Continuing their genre-bending experiments, Wheatley and co-writer/editor Jump return to themes familiar from their earlier work – men behaving like children; people trapped in confined spaces; the insane consequences of violence. Gleefully, they set Cillian Murphy’s IRA bagman Chris and Sharlto Copley’s South African gun-runner Vernon at odds, thanks to an explosive feud between Sam Riley’s black-eyed degenerate Stevo and Jack Reynor’s hot-headed, shaggy-haired Harry. Caught in the crossfire are Brie Larson’s deal-maker Justine, Armie Hammer’s suave Ord and Michael Smiley’s increasingly pissed-off Frank, with Patrick Bergin’s Howie sniping from the rafters and Babou Ceesay’s Martin taking one in the head. “I’m not dead,” explains the ex-Black Panther. “I’m just regrouping…”

When I interviewed Wheatley for the Observer last year, he spoke of the affectless “scale of destruction” of modern movies, and his longing for more intimate injuries on screen: “being hit by rocks or banging your fingers; small-scale stuff that we all know about”. Despite the endless rounds of ammo expended in Free Fire, it’s the masonry falling from above or broken glass crushed underfoot that does the real damage. There’s a touch of the DIY Straw Dogs siege-mentality at work here (Wheatley cites Sam Peckinpah as an influence), not least when Reynor shakes his pained knuckles after a flying crowbar dangs noisily on the barrel of his warm gun. When a pile of junk tumbles down a staircase over one poor unfortunate, you half expect a cartoon bowling ball to follow in its wake and crack someone on the head.

Wounds are painfully peripheral, with ankles, knees and ears bearing the brunt of the bashes. When Savile Row dandy (and “international asshole”) Vern gets shot in the shoulder, he’s told: “You’re gonna be OK – it’s mostly the suit.” And what suits! There’s a carnivalesque quality to the wardrobe, hair and makeup, with wide collars and ostentatious curls (“Charlie’s missing an angel”) lending colourful swagger to the performers’ movements, while neck scarves become eye-catching tourniquets.

Free Fire’s sharp jukebox choices chime with Martin Scorsese’s role as executive producer. With the Real Kids’ Do the Boob, which accompanies the opening overhead views of Boston (although the film was almost entirely shot in Brighton), and the use of John Denver’s Annie’s Song to provide Stealers Wheel-style counterpoint to the carnage, the 70s vibe is snappily evoked. But it’s Ex Machina composers Geoff Barrow and Ben Salisbury who add musical light and shade, moving from a plaintive western-inflected Spanish guitar theme through squishy keyboard arpeggios to punch-drunk percussive jazz beats as the rhythm of the gunfire increases.

Once the shooting starts, cinematographer Laurie Rose keeps his head down, the cameras crawling, crouching and scampering with the protagonists, occasionally leaping on to a gun barrel or an exploding gas canister to crank up the ante. From this raw front-line footage, Wheatley and Jump work editing wonders. There’s a real quilt-like beauty to the construction of Free Fire, creating a kinetic mosaic which imposes architectural order even as characters and storylines criss-cross like stray bullets.

The dialogue, too, has a sharp-shooter ring that the cast clearly relish, whether it’s Copley’s Afrikaans-accented puns (“watch and Vern”) or Murphy’s super-dry asides (“You should go [to Ireland]; they’d love you over there…”). When Ord is told he smells of perfume, Hammer injects real outrage into the manly retort “It’s beard oil!” As for Larson’s Justine, she’s not FBI but “IIFM – in it for myself”.

Best seen in a packed cinema, Free Fire cements Wheatley and Jump’s reputation as the UK’s most vigorously anarchic film-making duo. Unlike their hapless protagonists, they actually hit their targets. You’ll laugh, you’ll wince, you’ll duck. Bullseye!