Mag limits are pretty much pointless.
There is only one scenario where mag limits are of any concern- when two forces are combating. In non-combat life, it's a moot point. When response time is minutes, a second here or there reloading isn't going to matter.
When a shooter is walking into an area that is target-rich and with likely zero defensive capabilities, they know they have 3-5 minutes of uninterrupted time.
There's no possible way for LE to collect and destroy the millions of 20, 30, or 40 round magazines. It'd be like trying to round up all the Catcher in the Rye books.
Diane Feinstein uses a study on mag limits in Maryland (iirc) to advocate banning of "high capacity" magazines. But the conclusion she draws from the study is wrong. Mag limits won't prevent crime. Not even close. The study she quotes actually says at crime scenes, during the 1994AWB, high capacity magazines were found with less frequency than the time before the AWB. How does that show mag limits decrease crime?
There's another study that accounts for the crimes involving a gun, and I believe the average number of shots was 4. NSSF has a writeup:
http://www.nssf.org/factsheets/PDF/HighCapMag.pdf
What people lack is a frame of reference. What needs to be shown to the sheeple is a split-screen timed video. On one side, someone shooting 200 rounds in 10 magazines at a range. The other side, someone walking down the sidewalk, or waiting for a coffee, or jogging around a track. Then show another comparison with the estimated time Lanza took, versus people just walking. Show people how long 5 minutes really is. Then contrast that with the 15 seconds it'd take to open a gun safe (or a SRO response), sneak up behind the lil bast**d, and end the threat.
