We can't determine where the line is drawn unless people are willing to sit down and draw it. There is currently a political machine called the NRA that funnels only god knows how much money into preventing smart gun legislation (which, ironically, is the exact kind of legislation they were founded to help form) and preventing any gun legislation at all. They fear a slippery slope. The problem with that theory is that the only reason they fear a slippery slope is because their inaction in the face of violence turns dissenters more extreme. Had they been able to accomplish preemptive, smart gun legislation in the past, we would be able to approach this matter on a much more case-by-case basis, thereby preventing some sort of slippery slope, than we are now.
Every political overreaction is met with an opposite political overreaction, but be honest with yourself - how much of a slippery slope do you think there is? "Banning guns" is talking about overturning the Constitution. Good luck with that. That will never happen in this nation under any circumstance. What can happen is moderate, dynamic, and modern laws that fit our moderate, dynamic, and modern society. In this instance, a productive round table discussion has the potential to save thousands of lives a year.