User blog comment:Cfp3157/Season 1 Episode 6: Sicilian Mafia vs Triad/@comment-4555900-20120718055305/@comment-4661256-20120718063203

The AR-15 has severe issues with the barrel melting or breaking because of internal barrel pressure, basically nullifying its effectivess as a weapon if you use it in a long, fully-automatic burst like the Mafia will.