Abbreviation for the "Action Express" round seen used so often in Dersert Eagle pistols. Comes in 7 round clips and is extremely powerful, capable of punching a hole through light tank armor and easily penetrating kevlar vests. If the bullet is hollow point, it will enter the target (i.e. a 55 gallon barrel), and leave a hole the size of a nickel, but upon exiting leave a hole the size of a soda can.
A Desert Eagle, equipped with .50 caliber AE rounds is quite possibly one of the most powerful guns ever made.