According to Bill Still, and the video shot from the Uber driver in front of the Mandalay Bay hotel, one of the volley's heard was over 103 rounds, then an 84 round volley. Another volley of 72 rounds was recorded by someone else from a different location. I'm not familiar with clips or drums over 100 rounds that can be used for rifles, which leads to a belt fed machine gun. Everything is speculation though at this point, I definitely don't have all of the answers, or know for sure if we're listening to one gun or one shooter, it sure sounds like it though, at least in the ones before mentioned.