The dehumanising effects of combat come to the fore in Clint Eastwood’s visually powerful, but ultimately conventional examination of one man’s war.

Eastwood made his name playing masculine, violent men and since turning his hand to directing has largely stuck to his guns, to varying degrees of success.

His undisputed masterpiece, 1992’s Unforgiven, was a slow ride to hell as it laid bare the sickening emotional consequences killing someone might actually have on its assorted gunslingers, while his celebrated Gran Torino (2008) found its Dirty Harry protagonist forced to face both his own mortality and the changing face of his country.

In his latest, Eastwood’s stoical leading man is Chris Kyle, a “legend” among his brothers in arms for having chalked up 160 confirmed kills in Iraq and on whose self-explanatory book American Sniper: The Autobiography Of The Most Lethal Sniper In US Military History the film is based.

We are introduced to Kyle (Bradley Cooper) on just another day in Iraq, with a woman and child in his sights. They may be carrying an explosive device or they may not; it’s up to Kyle to make the judgement in order to keep his fellow marines safe.

The film flashes back to varying, defining points in his life, from a childhood hunting trip with his father in which he is taught to be a sheep dog to protect the sheep from the wolves, through to his decision to enlist as a US Navy Seal following the 1998 US embassy bombings. The red, white and blue-blooded all-American gets his chance to put his training into practice in the aftermath of 9/11 and the allied invasion of Iraq.

As Kyle racks up kill after kill – men, women and children – over the course of four tours, the cracks begin to show, both on his psyche and his marriage to Taya (Sienna Miller), while his notoriety leads to a bounty being placed on his head by the enemy.

Whilst visually arresting and bolstered by a central performance of considerable nuance and intensity by Cooper, American Sniper isn’t anything we haven’t seen before.

Kyle’s back story feels rushed, as if Eastwood is conscious of cutting to the action, while the Iraqis are either faceless enemies, cardboard cutout villains or fodder for Kyle’s sniper rifle.

The most promising character we see from the ‘enemy’ side is a Syrian sniper who incurs Kyle’s wrathful vengeance after shooting one of his friends. Steven Spielberg, who was on board to direct before walking away from the project, wanted to beef up the character and escalate the psychological warfare between the two shooters. It’s a premise that Eastwood, for good or ill, has chosen not to focus on.

Aside from a couple of unnecessary slow motion set pieces and a special effects shot of a bullet flying through the air that belongs in a cheaper movie, the various scenes of sharpshooting are disturbing in the matter-of-fact way they are portrayed. The rifle’s sights add an air of detachment from the death we are witnessing, with the exception of a horribly uncomfortable moment when a distressed Kyle has in his sights a young boy undecided whether to fire at an American convoy.

A particularly evocative sequence comes late on when Kyle and his buddies are engaged in a firefight during a sandstorm. It’s a potent image, loaded with hellish intent.

Miller is excellent, but is hamstrung by unoriginal dialogue (“Even when you’re here, you’re not here!”) and little screen time which undermines the scenes she and Cooper share back home. The director tries to emphasise Kyle’s worsening psychological scarring through these moments, but doesn’t give them the time to breathe.

Eastwood has fashioned an efficient and, at times, muscular war movie, but in spite of its cracking central turn American Sniper just misses its target.