Another reason for the need of semi-automatics is the main reason for the 2nd Amendment.
The 2nd Amendment wasn't written to allow us to hunt for food or sport. It was written to allow us to defend ourselves against a tyrannical government just like the one we have right now. No wonder the liberals are so intent on grabbing the guns even though it wouldn't stop mass murder. Anyone that is willing to kill will find a way to obtain what he or she needs to do the job and no laws will make any difference since they are already planning to commit a heinous crime that will guarantee the death penalty is in play.