The famous Browning Automatic Rifle. BAR-chan, Auntie, etc. The initial reward for starting the game early. Until then, kinda sadly, not as good. However, she will suffice in a pinch compared to other MGs due to her damage buff being unconditional (and better than M60's by default...).

See her mod entry here for info about her mod. At this point, she needs it to be relevant. More info about her in that entry.