Have any proof of that claim?    

We have choice to go with; unfounded accusations from all sides or, having professionals trying to rationally examine cases to determine the root cause.   Those that don't believe anything from a source of authority that conflicts with their opinion, will be upset.    (Without the studies, we can't know what the conclusions may be)

How much research money does the armaments industry spend toward the objective of  more effective killing?    Does your outrage reach to private contractors that equates violence with justice?    Maybe we invest in companies like BlackWater to protect us domestically?  Who needs courts, juries?

Our only good choice is to reform law enforcement, not turn it over to amateurs.   

You are completely right when you talk about ways of avioding danger that the individual can take.  But millions are trapped in neighbordoods that leave very few places to hide.  Only a minority wants to depend on winning a gun fight.