This thread is way off-topic, no matter where your stance on American gun laws.
It has come out that the man who did this shooting, clearly was paranoid, delusional, and very angry. He himself made the statement that "Jehovah told me to do these things", etc.
He made a lot of racist statements too.....but I honestly don't feel he was a racist because he hated white people, I think his underlying psychological disorders turned him that way. Also, the JW Cult upbringing of, "us vs. them" mentality really feeds into paranoid, delusional behavior.
The weapon he choose is of secondary concern. As stated before, he could have run them down with a truck, beat them with a baseball bat or club, etc. His underlying mental issues are the culprit of this behavior, and the fact that he didn't get help for said problems because he didn't feel he had them. (he did!!)