...is a good guy with a gun.
Not so much.
In the wake of the massacres this year at a Colorado movie theater, a Sikh temple in Wisconsin, and Sandy Hook Elementary School in Connecticut, we set out to track mass shootings in the United States over the last 30 years. We identified and analyzed 62 of them, and one striking pattern in the data is this: In not a single case was the killing stopped by a civilian using a gun. And in other recent (but less lethal) rampages in which armed civilians attempted to intervene, those civilians not only failed to stop the shooter but also were gravely wounded or killed. Moreover, we found that the rate of mass shootings has increased in recent years—at a time when America has been flooded with millions of additional firearms and a barrage of new laws has made it easier than ever to carry them in public places, including bars, parks, and schools. [Emphasis SFDB]