Plastic guns are stupid, after enough shots are fired the resin barrel will start to heat up. As we all know plastic melts when exposed to heat. A real gunsmith can carve an ar15 receiver from wood or machine press their own. This guy made a rifle with pieces from other guns.

The problem with these mass killings is that they committed by people who have a college education and show no signs of violence and just snap. Basically commited by smart people.