One of the problems here, Mr. Carberry, is the lack of focus on the people committing these crimes and blame being laid on whatever item was used. 
 A good read on this can help shed a little light I think: 
http://www.salon.com/2013/09/29/ronald_reagans_shameful_legacy_violence_the_homeless_mental_illness/

It doesn't matter what 'item' is used to commit murder. It can be an axe, a hammer, a brick, bare hands, or yes, a firearm. The common denominator of all the killings listed above was a person who had serious mental illness. And they were out on the streets due to the mental health bridge in America being systematically dismantled. This, in my belief, is a major reason these mass killings have become more common. If the gun-control crowd was more focused on helping the mentally ill and getting them off the street, I'd back their ideas. Unfortunately, they are focused on disarming law-abiding citizens, rather than appealing to Congress for help for the mentally ill.