American Sniper continues to dominate the box office and shows no signs of slowing down. The film has been nominated for six Oscars, with Bradley Cooper's performance as Chris Kyle earning him a nod for best actor.

Perhaps even more telling is how former Navy SEALs who have watched the film, have reacted:

“There are times when I forgot I was watching Bradley Cooper and not Chris himself.”

While actors work hard to portray their characters, there's something about what Cooper did that really shows he went the extra mile. Here are 5 ways Bradley Cooper dedicated himself to play badass American hero, Chris Kyle - the deadliest sniper in U.S. military history.

1. Eating around 8,000 calories a day. Which is nearly four times what your average American eats.

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2. Gaining thirty pounds of muscle in three months without using hormones or steroids.

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3. Training with Navy SEAL sniper, Kevin Lacz, who was on the same SEAL team as Kyle.

According to Lacz, Cooper was able to hit targets the size of a teacup at 800 yards on a second day at the range.

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4. Spending a few hours a day with a vocal coach to get Kyle's voice just right. Cooper told the Navy Times:

“I had this huge document that I put on my iPhone and my iPad and I just had it on constantly. I had earbuds on that whole time, just listening to his voice, repeating what he would say.”

5. Recognizing that Hollywood as a whole isn't supportive of these kind of films, Cooper's promise to Chris Kyle before his death that he would do everything he could do to accurately portray his story.

Cooper's dedication to tell Kyle's story is touching veterans and people everywhere.

More importantly, he did such a good job that Kyle's widow said, “This is how my kids will remember their dad.” And there is no better way to honor Kyle than that.