I watched a discussion today about that topic and one of the participants said that kdis learn how to use weapons when they play "killer games". He said that the guy in Erfurt and that Winneden guy only made shots for the head, like they did in counter strike. Yeah, of course, just because I play ego shooters I´m suddenly a uber-marksman who can pop headshots on 20m range with a pistol on moving targets. Too bad that both guys were familiar with firearms and had training with them... All in all every amok case needs to be carefuly investigated because it´s more a combination of environmental influences that turned them into monsters. It´s not just one thing that makes them go mad, it´s the pressure and anger they take with them. Instead of abreacting they collect it all untill they burst. Making strict laws even stricter won´t change anything if they´re getting bullied or miss-treated by their parents.