Boston Dynamics made a robot that can run

*plays Push it to the Limit in the background*

It wouldn't be too hard to mount a small caliber weapon with a small enough recoil to be absorbed by the weight of the bot and potentially be a jogging death machine. I mean they could put a 50 cal on it but they'd have to adjust the things movements for the recoil and it would probably fall over anyways but putting maybe an automatic .22 or .223 on it could be the start of the robot apocalypse.