The attorney general's office developed the guidelines after an investigation in 2011 found that private sales at gun shows often occurred without legally mandated background checks. (politico.com)
The «loophole» is that if two private individuals meet at a gun show, one can sell a gun to the other legally under the laws for individual sale. (politics.stackexchange.com)
The vendors at gun shows are already required to run background checks same as when they are at their places of business. (politics.stackexchange.com)