Rights are a funny thing. They are inherent to the very nature of our existence. The Constitution of the United States of America grants no rights. It only recognizes some of those rights and prohibits the nation created by that Constitution from violating those rights.
On another note . . .
Timmy4,
I think you are vastly underestimating how much a single individual can achieve after a minimal amount of training with a low capacity semi-automatic handgun. It is not an extraordinary feat hit a 10 inch diameter target at a range of 20 feet, once every second. If the shooter was using a 1911 45 caliber pistol, with a 7 round magazine, and if the reload time between magazines was a slow 2 seconds, that would easily allow the shooter 49 shots per minute. I'll round up to 50 for easy math.
Now, let's move the shooter to a mass shooting situation. Let's say that the shooter only hits with 1 out of 20 shots, or a 5% accuracy rate. Then let's say that it takes law enforcement 4 minutes to arrive, evaluate the situation, and stop the shooter. In those 4 minutes the shooter fires 200 rounds, with a total of 10 hits. The shooter has expended 27 magazines. There would be the potential for 10 victims of this mass shooter.
Now, let's add a concealed weapon licensee (CWL) into the scenario. We will assume that the CWL has the same weapon, the same skill, and is serious about self protection and so carries 3 total magazines. The CWL responds to the shooter and begins to return fire when the shooter is making the first magazine change.
At this point it is debatable as to whether the shooter would recognize the opposition of the CWL. To be honest, for this discussion it probably doesn't matter. In this second situation, there exists the possibility that the CWL will stop the shooter within the first 30 seconds of this encounter.
In neither situation was a magazine with a capacity over 10 rounds used. A magazine of twice the capacity used would only have a small impact on the number of bullets fired. 200 bullets compared to 210. ((240 seconds / 9 seconds per magazine) X 7 bullets per magazine = 187 bullets, 240 seconds / 16 seconds per magazine) X 14 bullets per magazine = 210 bullets). Okay, so that rounding up caused a bit of an error, but 187 bullets vs 210 bullets over the course of 4 minutes isn't that much.
Now, for a little bit of reality. 5% hit rate on a 10 inch target at 20 feet is low. At a shooting range, that would be considered poor shooting. However, with the stress of a real shooting conflict, it is possible. For people on the receiving end of this barrage, 5% would be a Godsend. In our scenario, the police response time was 4 minutes. Again, that would be a Godsend. At Sandy Hook Elementary, the reported response time from the first emergency call to the first officer on the scene (not when the shooter was stopped) was 20 minutes. It took 20 minutes for the first officer to arrive at a well known location, not 123 Random Street. In our scenario, that would equate to 935 rounds. Now, I cannot conceive how firing that many round from a handgun would feel like, but from a pistol cartridge rifle, 935 rounds would be easy. The magazine changes would get tiresome though.
While you might not believe it, but if the Sandy Hook shooter used a sawed off shotgun, the slaughter would have been increased many fold. A single shot of 3" buck into a group of school kids would have mown them down like wheat before a scythe. Short barreled shotguns were made illegal much like fully automatic machineguns were because of there extreme lethality. Unlike the machinegun though, a short barrel shotgun can be made by taking a hack saw to a regular shotgun.