Rate of fire
Head of Moms Demand Action (Shannon Watts) explains: https://twitter.com/shannonrwatts/statuses/396363030277414912
There were guns in the 1600's that exceeded that rate of fire, by a lot. Learn the basics you simpleton.
If you want to see what kind of person Shannon is, read this exchange, it says it all: loud, wrong, and not smart enough to know when to put down the megaphone.