Somebody grabbed the 'mule' at a pump event from Tony, and shot a video. Don't know the guy, but here is the video of the gun being shot.
Note, the mule is a test bed for the internals, which have very few changes between this and the final. People noted that the hopper was louder then the gun, along with the players and other guns shooting, even though the camera is right next to this gun. (h/t to D1PP1N on pbn)