We often talk about the difference in a terror attack between the jihobbyists, the want-to-be without training, and those with combat experience. How much does such make a difference in a act of terror... is a question that often is hard to answer. This article answers some of it.
"he had several small explosives on him, which he threw at the crowd to distract them every time he reloaded his Kalashnikov.2 Forensic analysis of the spent bullets shows that the last bullet in the magazines was a tracer round, giving him notice to reload. This is a fairly advanced military technique now used by the terrorists in Syria/Iraq. The attacker reportedly managed to reload his weapon three times, without being prevented by any security personnel or the general public, and was able to fire a total of 120 rounds in a span of about seven minutes"