There are statistics showing guns used far more often to stop a crime in progress.
I didn't track down reliable sources, but many right-wing media sources popped up, e.g.:
With yet another mass shooting prevented by a concealed carrier this past Sunday, we found it important to delve into the truth about gun ownership. The sources can be found here Guns save more lives than they take; prevent more injuries than they inflict * Guns used 2.5 million times a year in...
thinkaboutnow.com
When you consider that the U.S. has more privately owned firearms than people, more than all the guns of all the military in the world put together, it becomes apparent that the rate of gun violence compared to gun availability is quite small. I perceive that the problem is primarily justice system using kid gloves on violent criminals, catch-and-release, and the hogtying of law abiding citizens who would otherwise defend themselves and make violent criminals a dying breed.
We are allowed to use all necessary force to defend ourselves and others from certain crimes, including robbery, rape, murder. We do get to defend ourselves at home, and since past supreme court decisions, possession of a firearm at home has been a right. If someone enters a home by force in California, the resident may legally presume he is in danger of death or serious bodily harm (unless the intrude is current/former significant other, roommate, family member.) But outside the home has largely been gun-free zones (except for guns carried by criminals, who therefore have the upper hand.)