A word about "high powered assault weapons"
None of the weapons used in the Columbine, Virginia Tech, Aurora or Sandy Hook massacres were in fact "assault weapons", nor were any of them "high powered" in the conventional ballistic sense.
"Assault weapons" are by definition select-fire (meaning you can switch from semi-automatic to fully automatic with a selector switch) short-barrel carbines that generally fire pistol-caliber ammunition in order to reduce recoil when fired in fully automatic mode. Such weapons that are capable of fully automatic fire are already illegal.
As far as "high powered" goes....none of the weapons used in these massacres (with the exception of the 12 gauge shotguns used in Columbine) are considered "high powered" enough to even be legal to hunt deer with in the state of Oregon, or most others. Thats right...not only the 9mm pistol round but even the "high powered" .223 rifle round that so many wish to blame isnt powerful enough to meet Oregon regulations for the legal taking of deer.
Obviously, and tragically, these weapons were certainly "powerful" enough to take innocent human lives. But when the gun banners start talking about banning "high powered" weapons, what they would in reality be banning would be 100+ year old conventional hunting cartridges which are in fact far more "powerful" than the weapons used in the massacres. And when they talk of banning "assault weapons" they are talking about banning something that is already illegal in the first place. The reality...is that most of the politicians who are crying out for these bans dont know anything about guns in the first place, except what they "learned" by watching "A-Team" on TV back in the early 80's. They want to "ban" guns that look scary to them. They want to ban stereotypes of guns for purely emotional reasons and not factual ones.