Much rather deal with a known situation, than try to deal with an untrained muldoon on their own, with a Dirty Harry complex, shaky or nonexistent firearms skills, and absolutely no CQB training trying to resolve an active shooter situation in the presence of multiple non-combatants. No, the time one spends on a static known-distance range, hunting, or shooting road signs doesn't count. Nor does the day one spent on a "high-speed" range back in the National Guard. The people likely to be exposed these situations work in close-knit teams, & practice incessantly because the whole equation becomes much harder when the targets are hard to ID, move erratically, hide behind stuff, shoot back with intent to kill, and are surrounded by  people who are not targets. Statistically, depression, suicide, theft, and sexual assault are far, far more likely to occur than an active shooter on campus. These are real, quantifiable problems that will most likely only be made worse by more guns on campus.