Google AR-15 meltdown, the gun if it is a high end gun can fire thousands of rounds before a mechanical breakdown. I do not believe there was an AK-47 in the arsenal of the shooter's, I believe they were AR-15, and possibly an AR-10. I also believe the HealthRanger's acoustic sound analysis, hopefully he will do one on the JFK assassination as well. The scars part is that the FBI has these capabilities as well, and they have not deployed them, the question that needs to be asked is why not?