He had about 4 unassisted kills against full health enemies. The most obvious one is the one where he kills the guy trying to take the zone in the building, the teammate came so late he didn't even help in killing him. When he was shooting the guy outside of the building, he missed a lot of his shots, was not shooting for anywhere near as long as you said, and was way within range of the shotgun. He didn't kill the guy that came in in one magazine because he missed half of his shots and only had a total of two headshots in that time frame. That wouldn't kill anyone, regardless of weapon or level. EDIT:: rewatched it, he didn't even have two headshots, only one. He probably didn't even have more than 10 bullets connect. He's killing people as fast as I do with my Surrender A, which is my best PvP assault rifle. Whatever level advantage is there, it's so slight it doesn't matter.