Regular Joe Goes "Snap" and Shoots? Nope.

Cramer:

One of the enduring myths that underlies much of the gun control movement is the idea that a lot of murders are committed by ordinary people like you and I who lose their temper one day, grab a gun (because it's readily available), and murder someone...

The FBI studied this theory in the 1970s and found that it was not substantiable.

Same thing today. Cramer quotes Volokh:

...what we learn from the intentional homicide line in Justice Department's Felony Defendants in Large Urban Counties, 2004 (a sample that is representative of the large urban counties that account for roughly half of the nation's violent crimes):

83% had a prior adult arrest (compared to likely 25% or so of the adult U.S. population).

76% had two or more prior adult arrests.

55% had five or more prior adult arrests.

65% had a prior adult conviction.

44% had a prior adult felony conviction (compared to about 7.5% of the adult U.S. population, see Christopher Uggen et al., Citizenship, Democracy, and the Civic Reintegration of Criminal Offenders, 605 Annals Am. Acad. Pol. & Soc. Sci. 281, 288 (2006)).

IOW, there is a pattern of practice with murderers.

And it doesn't start with parking or speeding tickets.