Wow, an argument using actual logic that doesn't involve vague stats or "I don't think you need it and it scares me". I could get used to this. There is a flaw in your logic though.
I know I'm sounding like a broken record at this point, but a crazy in China killed 8 and wounded 6 with a knife, more kills than the Arizona shooter. If 30 round mags make it so easy to kill people, how can this be?
Now you can make the argument of the psychological factor involved in knifing someone vs shooting them, but anyone crazy enough to go on a killing spree is already beyond that point of deterrence IMO.
At most the argument for taking them away, IMO, is that we'd be taking away one method for crazies to go ape-shit. But as I and history have pointed out there are plenty of other, just as if not more lethal ways that no one seems to care about right now.
On a related note, McCarthy's fucking up with going for a 10 round mag limit. A lot of people out there own autos with between 10-20 rounds. It would criminalize these people and looks like she's just trying to smuggle in her renewed assault weapons ban on the heels of a crisis. If she had gone for 20 round limits maybe she would have gotten it.