S&W responded to the promotion concern in the industry forum with the following:
..."HI, Thanks for contacting S&W. To be clear, we are not limiting gun purchases in IL to 10 round magazines (Unless they are not allowed in the area being sold.), only the 3 free magazine offer is limited. Due to the multiple restrictions in certain counties, towns and cities in IL we are limiting the 3 free magazine promotion to 10 round magazines only. We do not have the ability to sort every submission based on a specific county or zip code, and due to the laws and penalties of shipping over 10 round magazines to a consumer in restricted areas, we will not ship anything over 10 rounds directly to any resident in IL for the 3 free magazine promotion. You can still purchase over 10 round magazines, if you county/town/city allows it. Regardless of state law, there are still several (Not just 1) cities, counties and towns that restrict magazine capacity. Thank you. S&W"...