why do vipers carry there AMRAAMS on the outermost rails?

i would like to know why USAF vipers carry the AMRAAM on the outermost wing rials. I have wondered this for a while, i think it looks good. But there must be an explanation for this, can anybosy help????http://www.onzeluchtmacht.nl/gallery/us/us50.jpg
i always thought that the winders would be able to go after a target better if stationed on the end of wing rails.