As a celebrity, Sean Penn is Hollywood’s disaffected dick emeritus — a fusty, cigarette-smoking scold who’s as serious about defending Jude Law’s actorly integrity at the Oscars as he is about lending a legitimate hand during international crises. At 54, he’s morphed from devil-may-care bad boy to angry, outspoken jerk, but few would question his cred; Penn is an authentic activist and asshole.

That speaks volumes to the proven versatility of Penn’s acting. This cur is as capable of buoyant joy (Milk) and withering wit (Sweet and Lowdown) as he is believable danger — whether it’s as a father we don’t quite trust (Mystic River), a more openly duplicitous scumbag lawyer (Carlito’s Way) or a spindly U.S. traitor (The Falcon and the Snowman).

The Gunman is yet another AARP ass-stomper action movie, but Penn’s mere presence makes it angrier than the rest. However, it strands that distinct animosity between the predictable airlessness of his celebrity cause-seeking and the live-wire lethality of his craft. Kudos for cramming a moral compass in its bandolier, but The Gunman ultimately feels stodgy, stiff and, rather primly upset with its pinky out when its knuckles should be bloodied with rage.

At least Penn isn’t trying to simply swipe Liam Neeson’s cheddar for a career-reimagining payday. For better or worse, Penn’s crusading public persona, coupled with a co-writing and producing credit here, is enough to persuade you he’s legitimately upset about a real-world problem at this movie’s core: Military contractors using a cover of peaceable security details to foment chaos in the name of corporate profit.

However, The Gunman suffers from its own economic conflicts of interest. It treats this topical fury as a chic accessory, swiftly forsaking the first act’s raw observations of oppression in the Congo for more photographable, less challenging U.K. and Spanish locales. So desperate is it to keep its hands clean — and its tax incentives intact — that the end credits apologize for suggesting that bullfights still exist in Barcelona. For a film so seemingly worked up about exploitation in the third world, it’s oddly sanitized and conciliatory.

Then again, maybe The Gunman is just a dumb action movie. After all, Jim Terrier (Penn) is no less ridiculous a character name than Lee Christmas or Trent Mauser, and he certainly seems like a slightly more erudite Expendable. Circa 2006, he’s part of a team purportedly providing security for a non-governmental medical organization in the Congo. Actually, they’re protecting lucrative mining interests by any means necessary — including the assassination of politicians who mess with their masters’ plans.

Terrier is the triggerman on a particularly destabilizing death, after which he must flee the continent and his lady-love doctor, Annie (Jasmine Trinca) — whom he correctly suspects jealous boss-man Felix (Javier Bardem) will romantically scoop up. Eight years later, Terrier is back in the Congo, his dirty deeds unknown to the humanitarian group he works for … until he’s suspiciously and specifically targeted by local toughs whose brains he ventilates at point-blank range. So begins Terrier’s long, un-strange and entirely obvious trip to find who wants him dead.

Boasting chiseled muscles and veiny biceps, Penn looks the part … and looks it, and looks it. Although interesting that the camera lingers on his body during sex scenes for a change, there’s enough dry-aged beef on display for five steakhouses. Taking an unexpectedly amusing page from 50 Cent, Penn eventually forgoes a shirt altogether for just a bulletproof vest.

As a result, the flesh fetish swings so far the other way that it places a laughable amount of focus on an acclaimed actor’s unexpected transformation, not the physicality of the character himself. That works with a wink and a smile, a la Colin Firth in Kingsman: The Secret Service, but not so much with Penn’s weary, droopy perma-squint. Penn labors to give Terrier some pugnacious personality tics and traits — such as his eye-rolling disdain at being denied a proper fight from a now ashen, alcoholic Felix — but it never quite closes the margin.

And that’s the best turn in a film with a murderer’s row like Bardem, Ray Winstone and Idris Elba to help out. As an Interpol agent, Elba prattles on with metaphors about termite-riddled tree houses; will someone please give this perpetual third-fiddle the keys to a damn franchise already? Winstone, as Terrier’s man at arms, could do this Motörhead-roadie-gone-to-seed bit in his sleep. And as Bardem bellows loudly and swills champagne amid a gun battle, you fear he’s given in to Jack Nicholson’s embarrassingly broad, lazy bad-guy caricature too soon.

The run-and-gun action is equally rote. Having once pioneered this fashionable subgenre with the still-superior Taken, director Pierre Morel must bemoan stitching together the frayed edges of last year’s threads — aping the black-ops retribution of The November Man and the ticking-clock brain injury of 3 Days to Kill. Here, being better than some means you’re only as mediocre as most.

The Gunman is an ill fit for Penn on any front — too tight to let his action-hero experimentation breathe and too loose for his geopolitical ire to take hold. In areas of art and altruism, it plays like something Penn probably loathes: “voluntourism.”