UPDATE: The conference paper discussed in this post was published in June 2016 in the journal Justice Policy and Research, in substantially the same form as discussed here.
Every time there is a mass shooting in America, some people look to ban large-capacity magazines in order to prevent similar tragedies from happening in the future. Cases in point: Colorado’s ban on magazines larger than 15 rounds following the Aurora theater shooting, and the New York SAFE Act’s post-Sandy Hook ban on magazines which hold more than 7 rounds of ammunition.
This led Kleck to ask whether bans on large-capacity magazines would have made a difference in the casualty counts of past mass shootings.
Note: This assumes, of course, that a large-capacity magazine ban would keep large-capacity magazines out of the hands of individuals who commit mass shootings – not a safe assumption at all, but one which Kleck allows for purposes of argument.
For this paper, Kleck identified and examined 88 mass shooting incidents in which more than six people were killed or wounded for the 20 year period from 1994 through 2013. He looked at incidents with more than six victims because six or fewer people could be shot with a traditional six-shot revolver with no large-capacity magazine needed. So he wanted to look at those events in which possession of large-capacity magazines would be most relevant.
Even with this restrictive definition of a mass shooting, Kleck found that large capacity magazines – defined as holding over 10 rounds – were used in only 21 of the 88 incidents (24%). So, in 76% of the incidents, a large-capacity magazine ban would have made no difference in any event.
Kleck then goes on to analyze further the 21 incidents in which a large-capacity magazine was used. In every case, the shooters carried either multiple guns or multiple magazines. Therefore, even without a large-capacity magazine, the shooters could easily switch guns or magazines.
Kleck also marshals evidence to show that the rate of fire of most mass shooters is so slow that having to change guns or magazines more frequently would not diminish their casualty counts.
There is much more detail in this 60+ page paper than I can recount here. I expect that Kleck will be publishing it soon for all to see.
For now, the bottom line is this: large-capacity magazines do not lead to higher casualty counts in mass shootings. It is the desire of the perpetrator to shoot a lot of people leads to higher casualty counts. The choice of a large-capacity magazine may reflect that desire, but it does not seem to facilitate its realization. Lacking large-capacity magazines, the shooters could realize their evil intentions with other widely available means.