Speaking to the Metro, retired US soldier Hank Keirsey, who previously taught military history at the West Point academy, spoke about how he became involved with the product.
He revealed that once the designers have picked a location and researched the conflict's background, he makes sure everything is accurate.
"I help them choose the right weapons for the conflict or, for example, educate them on the correct firing manoeuvre of a Wehrmacht rifle platoon in World War II," Mr Keirsey said.
He went on to reveal his interviews with veterans of conflicts portrayed in the game, which include talking to a US Army Ranger about his experiences in Iraq and Afghanistan.
According to the Chart Track game rankings, Call of Duty: Black Ops stands at number two in the UK.