Well, this isn't good. A robot at the Italian Institute of Technology led by Dr. Petar Kormushev has taught itself how to use a bow and arrow. It only took him eight shots to start hitting the bullseye every time. And I don't know about you, but I'm not sure that seven shots is enough time for me to run away.
The robot is an iCub, an open-source robot, so if you want one yourself you could build it, in theory. It's loaded up with ARCHER (Augmented Reward Chained Regression), a learning algorithm that allows him to learn how to hit bullseyes.
And you know that algorithm could be adjusted so he could use a sniper rifle instead of a bow and arrow. And then we're all screwed.