How to stop mass school shootings without destroying rights.

I tried posting this video earlier but for some reason the original posting does not work. Below is the text from the video

UPDATE!!! I just thought of something. If we gave all the kids in
schools paint ball markers with salt balls (which would be paint ball
shells full of salt and silicon dioxide), then these shootings could
likely be very effectively neutralized without using actual fire arms.
And there would be an advantage that the negative effects of friendly
fire would be very limited. The salt in the balls would cause the
shooter's weapon to jam, on top of hurting like crap upon impact and
along with severely effecting the shooter’s eyes and air passages,
especially with hordes of people firing them at the shooter. All
without destroying anyone’s freedom. This should be very effective.
Please write your representatives and push this idea. Please write
what you think in the comments section.