Notwithstanding the provisions of subsection (a) or any other provision of law, any person possessing a
firearm as defined in section 5845(a) of the
Internal Revenue Code of 1986 [formerly I.R.C. 1954] (as amended by this title) which is not registered to him in the National
Firearms Registration and
Transfer Record shall register each
firearm so possessed with the Secretary of the Treasury or his delegate in such form and manner as the Secretary or his delegate may require within the thirty days immediately following the effective date of section 201 of this Act [see subsec. (a) of this section]. Such registrations shall become a part of the National
Firearms Registration and
Transfer Record required to be maintained by section 5841 of the
Internal Revenue Code of 1986 (as amended by this title). No information or evidence required to be submitted or retained by a natural person to register a
firearm under this section shall be used, directly or indirectly, as evidence against such person in any criminal proceeding with respect to a prior or concurrent violation of law.