If you sell or dispose of more than one handgun to any non-licensee during a period of 5 consecutive business days, the sale must be reported on ATF Form 3310.4, Report of Multiple Sale or Other Disposition of Pistols and Revolvers, not later than the close of the business day on which you sold or disposed of the second handgun. The licensee must forward a copy of the ATF Form 3310.4 to the ATF office specified thereon, and another copy must be forwarded to the State police or local law enforcement agency where the sale occurred. A copy of the Form 3310.4 also must be attached to the firearms transaction record, ATF Form 4473, documenting the sale or disposition of the second handgun.
A business day for purposes of reporting multiple sales of pistols or revolvers is a day that a licensee conducts business pursuant to the license, regardless of whether State offices are open. The application of the term “business day” is, therefore, distinguishable from the term “business day” as used in the NICS context. Example: A licensee conducts business only on Saturdays and Sundays, days on which State offices are not open. The licensee sells a pistol to an unlicensed person on a Saturday. If that same unlicensed person acquires another handgun the next day (Sunday), the following Saturday or Sunday, or the Saturday after the reporting requirement would be triggered, the subsequent acquisition of a handgun would have to be reported on a Form 3310.4 by the close of the day upon which the second or subsequent handgun was sold.
[18 U.S.C. 923(g)(3), 27 CFR 478.126a]