Personally, I'm not exactly sure what "loophole" they speak of at times, because as a dealer myself and here in Arizona...you would be crazy not to do a NICS background check on anyone that purchases from your booth.
Honestly, according to the both U.S. Code and the Code of Federal Regulations, there really is not a "loophole" to speak of. What there is, however, is nothing that states in black-and-white doing the NICS at a gun show. Even though it is already stated in law, they just want it to be more specific. Honestly, they should just reword what is already law, but once again, our law makers can't read and want to have a new bill with their name on it.
Here are some of the laws that cover gun shows and tie right into the NICS background check.
The following information is eCFR Dated May 21, 2009
§ 478.100 Conduct of business away from licensed premises.
(a)(1) A licensee may conduct business temporarily at a gun show or event as defined in paragraph (b) if the gun show or event is located in the same State specified on the license: Provided, That such business shall not be conducted from any motorized or towed vehicle. The premises of the gun show or event at which the licensee conducts business shall be considered part of the licensed premises. Accordingly, no separate fee or license is required for the gun show or event locations. However, licensees shall comply with the provisions of §478.91 relating to posting of licenses (or a copy thereof) while conducting business at the gun show or event.
(2) A licensed importer, manufacturer, or dealer may engage in the business of dealing in curio or relic firearms with another licensee at any location.
(b) A gun show or an event is a function sponsored by any national, State, or local organization, devoted to the collection, competitive use, or other sporting use of firearms, or an organization or association that sponsors functions devoted to the collection, competitive use, or other sporting use of firearms in the community.
(c) Licensees conducting business at locations other than the premises specified on their license under the provisions of paragraph (a) of this section shall maintain firearms records in the form and manner prescribed by subpart H of this part. In addition, records of firearms transactions conducted at such locations shall include the location of the sale or other disposition, be entered in the acquisition and disposition records of the licensee, and retained on the premises specified on the license.
[T.D. ATF–270, 53 FR 10498, Mar. 31, 1988, as amended by T.D. ATF–401, 63 FR 35523, June 30, 1998]
Ok, here is the part about the NICS background check...
§ 478.102 Sales or deliveries of firearms on and after November 30, 1998.
(a) Background check. Except as provided in paragraph (d) of this section, a licensed importer, licensed manufacturer, or licensed dealer (the licensee) shall not sell, deliver, or transfer a firearm to any other person who is not licensed under this part unless the licensee meets the following requirements:
(1) Before the completion of the transfer, the licensee has contacted NICS;
(2)(i) NICS informs the licensee that it has no information that receipt of the firearm by the transferee would be in violation of Federal or State law and provides the licensee with a unique identification number; or
(ii) Three business days (meaning days on which State offices are open) have elapsed from the date the licensee contacted NICS and NICS has not notified the licensee that receipt of the firearm by the transferee would be in violation of law; and
(3) The licensee verifies the identity of the transferee by examining the identification document presented in accordance with the provisions of §478.124(c).
Example for paragraph(a). A licensee contacts NICS on Thursday, and gets a “delayed” response. The licensee does not get a further response from NICS. If State offices are not open on Saturday and Sunday, 3 business days would have elapsed on the following Tuesday. The licensee may transfer the firearm on the next day, Wednesday.
(b) Transaction number. In any transaction for which a licensee receives a transaction number from NICS (which shall include either a NICS transaction number or, in States where the State is recognized as a point of contact for NICS checks, a State transaction number), such number shall be recorded on a firearms transaction record, Form 4473, which shall be retained in the records of the licensee in accordance with the provisions of §478.129. This applies regardless of whether the transaction is approved or denied by NICS, and regardless of whether the firearm is actually transferred.
(c) Time limitation on NICS checks. A NICS check conducted in accordance with paragraph (a) of this section may be relied upon by the licensee only for use in a single transaction, and for a period not to exceed 30 calendar days from the date that NICS was initially contacted. If the transaction is not completed within the 30-day period, the licensee shall initiate a new NICS check prior to completion of the transfer.
Example 1 for paragraph(c). A purchaser completes the Form 4473 on December 15, 1998, and a NICS check is initiated by the licensee on that date. The licensee is informed by NICS that the information available to the system does not indicate that receipt of the firearm by the transferee would be in violation of law, and a unique identification number is provided. However, the State imposes a 7-day waiting period on all firearms transactions, and the purchaser does not return to pick up the firearm until January 22, 1999. The licensee must conduct another NICS check before transferring the firearm to the purchaser.
Example 2 for paragraph (c). A purchaser completes the Form 4473 on January 25, 1999, and arranges for the purchase of a single firearm. A NICS check is initiated by the licensee on that date. The licensee is informed by NICS that the information available to the system does not indicate that receipt of the firearm by the transferee would be in violation of law, and a unique identification number is provided. The State imposes a 7-day waiting period on all firearms transactions, and the purchaser returns to pick up the firearm on February 15, 1999. Before the licensee executes the Form 4473, and the firearm is transferred, the purchaser decides to purchase an additional firearm. The transfer of these two firearms is considered a single transaction; accordingly, the licensee may add the second firearm to the Form 4473, and transfer that firearm without conducting another NICS check.
Example 3 for paragraph(c). A purchaser completes a Form 4473 on February 15, 1999. The licensee receives a unique identification number from NICS on that date, the Form 4473 is executed by the licensee, and the firearm is transferred. On February 20, 1999, the purchaser returns to the licensee's premises and wishes to purchase a second firearm. The purchase of the second firearm is a separate transaction; thus, a new NICS check must be initiated by the licensee.
(d) Exceptions to NICS check. The provisions of paragraph (a) of this section shall not apply if—
(1) The transferee has presented to the licensee a valid permit or license that—
(i) Allows the transferee to possess, acquire, or carry a firearm;
(ii) Was issued not more than 5 years earlier by the State in which the transfer is to take place; and
(iii) The law of the State provides that such a permit or license is to be issued only after an authorized government official has verified that the information available to such official does not indicate that possession of a firearm by the transferee would be in violation of Federal, State, or local law: Provided, That on and after November 30, 1998, the information available to such official includes the NICS;
(2) The firearm is subject to the provisions of the National Firearms Act and has been approved for transfer under 27 CFR part 479; or
(3) On application of the licensee, in accordance with the provisions of §478.150, the Director has certified that compliance with paragraph (a)(1) of this section is impracticable.
(e) The document referred to in paragraph (d)(1) of this section (or a copy thereof) shall be retained or the required information from the document shall be recorded on the firearms transaction record in accordance with the provisions of §478.131.
(Approved by the Office of Management and Budget under control number 1140–0045)
[T.D. ATF–415, 63 FR 58279, Oct. 29, 1998, as amended by ATF–11F, 73 FR 57241, Oct. 2, 2008]
So...where is the "loophole"????