There is another completely free app called Gun Free Zones. http://www.gunfreezoneapp.com/
There is an AP available on Android and Iphone. Android has a free and paid version. Paid version is ad free and $2.99.
Easy interface, shows a map with flags and below it list of business' and whether they are 2A friendly (green flag pro, red flag anti and white flag not yet rated)
Doesn't look like there is anyway to judge OC specifically, but when rating a business, there is a comment section which can be noted and viewed by others. I think this a great tool if enough people start to use it.