More about the rate of fire... the original BARs actually had an adjustable rate of fire, but came issued at the beginning of WWII set to the lowest rate because the box magazines that were issued only held 20 rounds. The gun was supposed to be a sort of "SAW" weapon, but really just turned into an automatic M1 Garand. In the later years of the war, the BAR had the adjustable rate of fire feature removed, as it proved to complex for the battlefield. However many BARmen spent a lot of time with their rifles and figured out to up the rate of fire, cut down the barrel, extend the magazines, and for the very inventive, set it up to fire .30 machine gun ammo (the kind on belts). Pretty useless information, but good ideas for customization in the future if your into that sort of stuff.
edit : 20 rounds in box mag. damn that sticky zero key