Also put your head in a bucket of water while you play it will improve your hit percentage
A Rank on Socom 3 is about as important as a rock in a garden. Its there so woopie! but it doesn't do squat, won't change your life, and if it was taken away I am sure no one would give a ****. All in all don't worry about your rank on a video game.
Have fun, enjoy the game while you can.