How many americans are accidently killed by guns owned by "honest people" such as the father shooting the son because he thinks he's a burglar when the son comes back home at 3AM
How many "killers" are killed by "honest people" such as the father shooting the burglar who entered his house at 3AM
This kind of statistic would help decide if the open access to guns is a good policy or not, one could always argue that if all the students were carrying guns they could have shot the maniac, but if the laws were tougher the maniac could not buy all his equipment.
For sure real criminals could get the guns anyway but whene was the last time that a real criminal went to a school and shot people before shooting himslef, real criminals go to BANKS, try NOT to shoot anybody (less jail if you're caught) and then try to RUN AWAY (and not commit suicide)
The bottom line is that real criminal are less dangerous regarding schools that maniacs because they are predictable (criminals) and maniacs are by definition unpredictable...
One interesting thing about american society is that some of your problems (voting system and guns for example) seem to be so easily solvable that it's a wonder for the rest of the world that you don't and still listen to Charlton HESTON and the DIEBOLD guys telling you "it's in the constitution", I'm sure the guys who wrote the constitution didn't have GUNS at SCHOOL in mind, what's the next step, tasers at kindergarten ?