About the Fuss Over HK Sears

922(o)

(1) Except as provided in paragraph (2), it shall be unlawful for any person to transfer or possess a machinegun.
(2) This subsection does not apply with respect to—

(A) a transfer to or by, or possession by or under the authority of, the United States or any department or agency thereof or a State, or a department, agency, or political subdivision thereof; or
(B) any lawful transfer or lawful possession of a machinegun that was lawfully possessed before the date this subsection takes effect. [Emphasis added]

Nothing about registration in the "post sample" law. And the part of the law that allows the manufacturer to file the registration form the next day:

§ 479.103 Registration of firearms manufactured.

Each manufacturer qualified under this part shall file with the Director an accurate notice on Form 2 (Firearms), Notice of Firearms Manufactured or Imported, executed under the penalties of perjury, to show his manufacture of firearms. The notice shall set forth the name and address of the manufacturer, identify his special (occupational) tax stamp and Federal firearms license, and show the date of manufacture, the type, model, length of barrel, overall length, caliber, gauge or size, serial numbers, and other marks of identification of the firearms he manufactures, and the place where the manufactured firearms will be kept. All firearms manufactured by him during a single day shall be included on one notice, Form 2 (Firearms), filed by the manufacturer no later than the close of the next business day. [Emphasis added] The manufacturer shall prepare the notice, Form 2 (Firearms), in duplicate, file the original notice as prescribed herein and keep the copy with the records required by subpart I of this part at the premises covered by his special (occupational) tax stamp. Receipt of the notice, Form 2 (Firearms), by the Director shall effectuate the registration of the firearms listed on that notice. The requirements of this part relating to the transfer of a firearm are applicable to transfers by qualified manufacturers.