Reasons to Ban All Guns in the United States:
In 2011 alone, a total of 478,400 fatal and nonfatal violent crimes were committed with a firearm, as noted by the Special Report on Firearm Violence, 1993-2011, published in May 2013 by the Bureau of Justice Statistics. The same report states that a shockingly high 8% of all violence was committed with a firearm. If firearms had been banned in 2011, the most recent year in the report, there would've been 25% fewer robberies and 69% fewer homicides.
According to the above-mentioned report, only 0.8% "of victims in all nonfatal violent crimes reported using a firearm to defend themselves during the incident" in the years 2007-2011. This included instances where the victim "threatened" their assailant with the use of a firearm as well as occasions where a firearm was actually fired in self-defense.
From 1993-2011, only 0.6% of firearm violence was committed in gun-free school zones. Compare this with 19.3% of said incidents occurring in the home or lodging of the victim, 22.7% occurring near the victim's home, 8.8% at a commercial establishment, and 22.9% in public spaces. In fact, the notoriously gun-free school zones had the lowest incidence of firearm-related violence out of any classification in the BJS's report (which spanned nearly two decades) and that's even when you include crimes that occurred when the victim was "on school property, on the way to or from regular sessions at school, and while attending or traveling to or from a school-sponsored event."
After nonfatal crimes involving firearms, 31% of those who did not report it did so for fear of reprisal; compare this with just 5% of violence that didn't involve a firearm. Conversely, 36% of victims of non-firearm violence were able to resolve the situation without involving police, compared to just 12% of firearm violence victims. A shocking 27% of firearm violence victims reported that "police could not or would not help," while only 16% of non-firearm violence victims said the same.
Source for stats: bjs.gov