Adds a new permitted use (subparagraph (J)) to 34 U.S.C. 10152(a)(1) allowing Byrne grant funds to be used to compensate for surrendered semiautomatic assault weapons and large capacity ammunition feeding devices under buy-back programs.

Reorganizes and modifies subsections (s) and (t) of 18 U.S.C. 922: repeals existing subsection (s); redesignates subsection (t) as subsection (s); adds a definition of 'chief law enforcement officer' to subsection (s) as redesignated; and inserts a new subsection (t) establishing background-check/transfer custody requirements for transfers of 'grandfathered semiautomatic assault weapons' by unlicensed persons plus exceptions and Attorney General rulemaking authority.

Modifies the prefatory matter of 922(y)(2) by removing a cross-reference to a specific subparagraph of subsection (s) and altering the listed cross-references.

Updates a cross-reference in the prefatory matter to refer specifically to section 922(s).

Replaces existing occurrences of a referenced term with an explicit reference to section 922(s).

Alters a cross-reference in the prefatory matter of section 103(l) of the Brady Handgun Violence Prevention Act (codified at 34 U.S.C. 40901(l)), changing a reference from subsection (t) to subsection (s).

Amends 18 U.S.C. 924(a)(1)(B) by replacing the reference to subsection (q) of section 922 with references to subsections (q), (r), (v), (w), and (aa) of section 922.

Adds the phrase 'Assault Weapons Ban of 2025' at the end of subsection (i) of 18 U.S.C. 923 (as amended by this Act).

Amends subsection (d) of 18 U.S.C. 924 by inserting additional cross-references and by modifying paragraph (1) to include references to the new subsections (v) and (w) (and other unspecified insertions indicated in the amendatory text), and by making related insertions in paragraphs (2)(C) and (3)(E).

Adds new paragraph definitions (numbered (39) through (54)) to 18 U.S.C. 921(a).