Thanks for the responses to my questions, from various people, they've given me some insight.
I think one question I asked didn't get an answer or perspective though. (or maybe I missed it!). It was pointed out that more people die from homicides or accidents with handguns than with these "assault" or "military style" weapons. I have no doubt that's true. However, it also seems to be the case that these horrific mass killings have mostly been done with rifles such as the one used for the last massacre.
Even if statistically, these weapons kill less people, surely there's something - ideological? if that's the right word? (probably not) - to be looked at here? Why do these crazy, heartless people who kill a group of defenceless children, a bunch of moviegoers, whatever, choose these types of weapons in particular? Is it that they are being glorified? Does the presence of the weapons help to give them the idea? (like, this guy's mother was really into guns and had a collection including this type of weapon?)