User blog comment:SlyCooperFan1/Assault Horizon A Ranks.../@comment-99.142.27.230-20111127052705/@comment-1824272-20111207031853

@XLawXc Each mission has a specific point value that you need to surpass in order to attain an A rank. The higher the difficulty, the more points you get, therefore the easier it is to get to the A rank.