I have seen every James Bond film made and can explain the red mist.

Egg is completely correct that what you are seeing is the rifling on the interior of the barrel. What you need to realize is that you are standing in the position of an assassin trying to kill 007. 007 walks on to screen and the barrel follows as the assassin tries to aim. James Bond is too quick and snaps out a shot which fatally wounds the assassin. The red mist is a metaphor for the assassin's death as blood pours from the gunshot wound.

After that little explanation I need a Vodka Martini - shaken not stirred...