"Know" or "believe"?
Armed Resistance to Crime: The Prevalence and Nature of Self-Defense With a Gun | Office of Justice Programs
Simulations have some value, but real world data
are better. A problem is that sources one would
expect to have an agenda pro or con gun rights
typically have research results supporting the
expected conclusion, eg, Gary Kleck vs Harvard.
One thing is clear...it, that guns are often used
for good, & often used for evil. Given that in our
culture & legal environment, guns won't be
eliminated, the issues are about curbing the
evil usage, & keeping the good.