Gun Control & RKBA

But what metric am I supposed to use?

I tried to search for statistics on defensive gun uses. I found pages that state over two million defensive gun uses per year. I found pages that refute the figure most of which use justifiable defensive homicides as their yardstick for effective defensive gun use.

The most accessible analysis of defensive gun use statistics I have found is from the Violence Policy Center, where they strenuously reject the notion of over two million defensive gun uses per year.

http://www.vpc.org/studies/justifiable15.pdf

In the course of debunking the over two million figure, they come to the conclusion that "only 235,700" defensive gun uses occurred during the five year period of study:

"During this same five-year period [2007 to 2001], only 235,700 of the self-protective behaviors involved a firearm. Of this number, it is not known what type of firearm was used or whether it was fired or not. The number may also include off duty law enforcement officers who use their firearms in self-defense."

235,700 divided by 5 is 47,140. I rounded that up for simplicities' sake, but I'll continue with the 47,140 figure as an average for defensive gun uses per year.

These statistics were drawn from the National Crime Victimization Survey (NCVS) conducted by the Bureau of Justice Statistics. These are statistics on violent crime, not saving big screen tvs or bbq grills. For “violent crime” the NCVS measures rape/sexual assault, robbery, and aggravated and simple assault (see Bureau of Justice Statistics, “Violent Crime,” (see http://www.bjs.gov/index.cfm?ty=tp&tid=931). That falls well into the situation where the victim faces an imminent risk of serious bodily injury or death.

So I'll take that number: 47,140 defensive gun uses per year as determined by the Bureau of Justice Statistics, and (since I'm using exact figures) compare it to 11,994 deaths by firearm (due to homicide, accident, and undetermined intent) for the year 2015, according to the CDC:
http://www.cdc.gov/nchs/data/nvsr/nvsr64/nvsr64_02.pdf

You do the math yourself, and tell me how many more people are alive because they were able to make the choice to use a firearm to defend their self.