Blaming the wrong people

Uhm, it's neither nerdy videogamers nor gun manufacturers and dealers who are responsible for violent kids.

It's parents themselves.

And there is ample daylight between between parents who prohibit their kids from playing videogames and ones who are largely inactive in violence-related aspects of their children's lives. Sanity lies in-between these extremes.

Certainly parenting is an inexact science art and no one can be responsible for everything their child does. But a sane parent provides sound guidance, and that guidance will do far more to prevent kid violence than banning 100% of videogames or movies or guns ever could.

Besides, if you banned guns they'd get accustomed to violence with something else, like knives in the UK.