The ATF may want to regulate long guns by requiring multiple purchases to be reported, but I think it’s almost certain they have no authority to do so. Handguns require this form, but that is because 18 USC Section 923(g) gives ATF that power explicitly:
(3)(A) Each licensee shall prepare a report of multiple sales or other dispositions whenever the licensee sells or otherwise disposes of, at one time or during any five consecutive business days, two or more pistols, or revolvers, or any combination ofÂ pistols and revolvers totalling two or more, to an unlicensed person. The report shall be prepared on a form specified by the Attorney General and forwarded to the office specified thereon and to the department of State police or State law enforcement agency of the State or local law enforcement agency of the local jurisdiction in which the sale or other disposition took place, notÂ later than the close of business on the day that the multiple saleÂ or other disposition occurs.
If Congress had intended ATF to have the power to require this form for long guns, they well knew how to do so, but chose to limit the requirement to pistols and revolvers. The fact that shotguns and rifles are not included in this statutory requirement is indicative that ATF does not have the power to require this for long guns at all. This is a power grab by the agency, pure and simple.