If i'm not mistaken there was research done recently that disproved this myth regarding Chicago's guns and where they come from but can't put my finger on it right now.
Chicago gangs don
Gangs Look To The Suburbs For Guns: Chicagoist
http://www.wgntv.com/news/wgntv-gun...re-bought-in-suburbs-20120827,0,4394301.story