May I invite your attention to:
A United Kingdom newspaper's display of American gun laws,
5 stages of violence,
Video explaining why governments disarm their people.
The primary reason for carrying an extra magazine
is to fix stoppages, not because you fear running out
of ammunition. We are not police. We are not military.
The probability of being forced to engage in a prolonged
gun fight is infinitesimal. Statistically speaking,
the gun fight last 2 seconds, one or two rounds are
fired from a distance of 5 feet; at which point one
side has fled or is incapacitated. But, the probability
of a stoppage is high, due to contact with persons,
clothing, walls, etc. If you fire from inside your
jacket pocket or inside your purse, the confined space
may prevent the brass from ejecting properly
(may prevent the brass from extracting properly).
That's why revolvers are so nice in confined spaces.