Without a very strong stop and frisk and severe penalties for carrying without a license not much. You would also have to make concealed carry a little more difficult to license. You would still want to give "qualifies and vetted" citizens to ability to conceal carry but it is much to easy. There are thousands of felons out there who have not been convicted yet that can purchase and carry a firearm, you see them shooting at each other at stop lights. The second amendment has been twisted so much it is not recognizable. WE need to do something besides make more guns for good guys.