You remember the six-shooter that magically fired 41 times in Westerns of yore, today embodied by a sloppy movie’s “endless” gun clip in combat or cop thrillers?

“One Shot” throws a fresh goof into the cinema fan’s lexicon. It’s the villain transport clown car. In “One Shot,” a single Eastern Bloc troop truck offloads what seems like 127 mercenary/terrorists onto a stony CIA “black island” in the Baltic, armed men of many cultures and languages there to break an accused terrorist out of a “black ops” prison.

We all laugh at all the clowns that pile out of a clown car. I laughed at all the bulky mugs toting AK-47s pouring out from under the canvas flap on this truck, which is a “Stargate” wormhole into Mercenaries-R-Us, from the looks of it.

The gimmick built into this thriller starring B-movie badass Scott Adkins (“Debt Collectors,” “Expendables 2”) is that it’s filmed in a long of long takes, the film buff’s beloved “One Shot.” on display in the movie’s trailers, too, but taken to its logical extreme in a few films over the years, most recently “1917.”

That gets your attention, although in the hands of director James Nunn (sequels to “The Marine” and “Green Street,” “Tower Block”) it is used in ways that doesn’t put the viewer on edge by building suspense.

It’s still impressive, here and there, the sweeping hand-held tracking shots that brings Lt. Harris and three other SEALs and a CIA analyst (“Twilight” alumna Ashley Greene, billed as Ashley Green Khoury here) to “Black Island” to retrieve a detainee (Waleed Elgadi) who might know something about an imminent terrorist attack.

What’s more impressive is the gunplay choreography that sees Adkins shoot his way through scores and scores of villains — first-person shooter video game style — rolling, falling down, tumbling out of explosions, popping this guy and that guy in the head, this other fellow in the knee first so that his head drops down to Lt. Harris’s level for the kill-shot.

The story? It’s a patchwork mess about Lt. Harris and Analyst Anderson running afoul of the base director (Ryan Phillippe) who is hell-bent on not releasing his prisoner to him.

And then the burly bad guys (Jess Liaudin plays their leader) pile and pile out of that clown truck, and the base is mostly wiped out, the survivors holding out with the “person of interest” that both sides covet.

The acting is somewhat indifferent, a risk you run when your technical concern, “How do we get this scene in one long take?” is paramount.

The film stumbles to a halt several times, for arguments, complaints, silly pauses for this or that SEAL to do a Tarantino speech about “When I’m in heaven, before my God” as he’s shooting this bad guy and then that one. And one half in the forward momentum comes when the terrorist leader convinces one of his underlings to Take One for Allah and strap on a suicide vest.

The dialogue is hard-boiled combat film cliches warmed over — “We ain’t leaving any more people here today,” “Nothing wrong with being scared, OK? It’s what you DO with the fear that really counts.”

I could have done without the base second in command (Terence Maynard) sneering about “new administration, new priorities — ‘domestic terrorism,'” as if Jan. 6 and events like it weren’t happening. When everything goes down, he blurts out “Just like Benghazi,” like John Boehner weeping that he’ll die on that phony scandal hill.

But that’s a handy dog whistle for the “One Shot” target audience, I guess. The B-movie they’re targeting for them? Not all that, “one shot” long takes and clever combat choreography notwithstanding.

Rating: unrated, graphic violence

Cast: Scott Adkins, Ashley Greene Khoury, Ryan Phillippe, Waleed Elgadi, Jess Liaudin and Terence Maynard

Credits: Directed by James Nunn, scripted by Jamie Russell. A Screen Media release.

Running time: 1:37