...who's lobbying quite specifically did not help prevent hundreds of deaths
Actually, it probably prevented a damn sight more deaths. Places that have concealed carry & castle doctrine have drastically lower rates of violent crime than those that don't. What has Chicago's handgun ban given them? One of the highest murder rates in the US.
If you're trying to pin the Colombine deaths on Heston, then I'd suggest that had his lobbying been more successful (i.e. to the extent that the teachers were allowed to carry), then there would have been fewer deaths in that tragic incident.
Are you sure you're not making the effect a cause here?
I've seen this argument before (The area was different, could have been some NY ghetto, but the points were the same), And I thought surely, this is because:
Chicago -> poor (?) -> unemployment -> crime -> shootings -> handgun ban
rather than:
Chicago -> evil liberals impose handgun ban

-> Criminals shoot people because it's become more illegal.
Also, do you really think armed teachers are a good idea? For a start, teachers want to teach, not kill children, no matter how urgent the situation is.
Also, I've seen teachers have mental breakdowns in class. what's to say that someone in the grip of madness won't pull a gun on a student?
I know I've half-contradicted myself, but the situations are different.
I'm not meaning to troll here, I'm just curious.