Chicago has a provision within the city code (8-20-085) that states that the carry, possession, selling, offering, or displaying for sale of any high capacity magazine is unlawful. Certain exceptions are included for members of law enforcement and the military. This type of magazine limitation is not entirely unique in the United States with a handful of states and other local municipalities having similar restrictions.
The definition of a high capacity magazine is set forth as:
High capacity magazine” means a magazine, belt, drum, feed strip, or similar device, including any such device joined or coupled with another in any manner, that has an overall capacity of more than 15 rounds of ammunition. A “high capacity magazine” does not include an attached tubular device to accept, and capable of operating only with, .22 caliber rimfire ammunition.
The limitation of 15 rounds seems fairly arbitrary but it certainly could be worse (Try NYC). For most Chicago Illinois Concealed Carry permit holders this limitation isn’t overly problematic as most concealed firearms don’t carry 15 rounds or more anyway… but there are plenty of exceptions and plenty of us concealed carry holders that are frustrated.