A really really
big gun designed to put down and stop
raging mobs of people rather quickly. Generally used by
policemen behind
Lexan shields with
bulletproof vests on.
Riot guns generally try to get across the following impression:
Hello. I am a riot gun. I have a long, long serial number and unit name involving references to long dead cats and powerful sounding 'B movie' monsters. An example of this is "Unit XR31337-A5-QDIE-WHISKASREVENGE-LOKORTHEDEATHMONSTER-561290532324-Z". I am here on the sole mission of taking you and destroying you as quickly as possible. I apologize for any bodily harm or inconvenience in your schedule this might cause. NOW MOVE OUT OF THE WAY! Have a nice day. Please pull up to the first window.
Also, riot guns are noted for their ability to shoot almost anything shootable.