Long gone are the days of Bradley Cooper playing second to the leading man. The American actor has gone from strength to strength since the funny days of all three Hangovers and his break-out lead role in the thriller Limitless. Recently he has commanded the main man and has done so in the hit drama Silver Linings Playbook and the comedy crime drama American Hustle – both big Oscar-winning productions.

Bradley Cooper
Bradley Cooper plays the lead in American Sniper

Now he’s at the centre of American Sniper, a biographical action film directed by Clint Eastwood based on the life of United States Navy Seal Chris Kyle.

The movie charts Kyle’s tour of duty in Iraq and his struggles to be a good father and husband during his deployment.

Portraying such an important story and depicting such a specific character, Cooper admits that there was a lot of research and preparation that had to go into the film.

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He said: "Chris was 230lbs. He was a monster and I just said there’s no way. If I don’t believe I’m Chris then no one else is going to believe I’m Chris.

"I need to figure out how he talks and how he walks and the only way to do that was to try to get as big as he is. That was just to get to a point where I could start to believe that I was him."

Cooper continued: "I did a lot of research and there was tons out there. It felt like I had an honour to pretend to be him and I loved every moment of walking in his shoes."

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Chris Kyle completed four tours of Iraq and he is listed as having 160 reported kills which is the most kills per sniper in American history, by a long shot.

But it’s not just about the death and destruction that war can bring to one person and the country they’re in. The film also touches on the people that Chris Kyle left back home.

Cooper said: "The other thing about this movie is that it’s a wonderful love story. Taya Kyle, Chris’ wife, played by Sienna Miller, really matches him with energy and strength.

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"You have these two very strong characters who come in contact with each other and there’s a lot of fire, love and pain because of it."

Tragically, Chris Kyle was shot and killed at a shooting range in February 2013, along with his friend Chad Littlefield.

Cooper said: "This is his story. It’s a story about this man, what it was like to become a seal and balancing the life of being a soldier of war and a father at home and what that did to him."