If we are using this video https://www.youtube.com/watch?v=uCsdPszJLNQ as evidence for realistic running look at the Chief from 48 secs to the end. The barrel of the rifle is pointed to the side rather then at a up ward angle we see in that gif. Look at the way you see games like REACH, H4 and Battlefield hold rifles and weapons when they are sprinting. They hold the rifles to the side rather then all over the place you see in COD.
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