; and (ii) by adding at the end the following: Not later than 60 days after the date of enactment of the Ammunition Background Check Act of 2018 , the Attorney General shall promulgate rules defining significant quantity for the purpose of this paragraph. ; and (E) in paragraph (7), by inserting or any quantity of ammunition after 1 or more firearms . (2) Conforming amendment Section 4182(d) of the Internal Revenue Code of 1986 (relating to exemptions relating to firearms) is amended by inserting and except as provided in paragraphs (1)(A) and (3)(C) of section 923(g) of title 18, United States Code, before no person holding a Federal license . (e) Making it a crime To steal ammunition Section 922(u) of title 18, United States Code, is amended— (1) by inserting or ammunition after in firearms ; and (2) by inserting or ammunition after any firearm . (f) Keeping ammunition out of the hands of juveniles Section 922(x) of title 18, United States Code, is amended— (1) in paragraph (1)(B), by striking only ; and (2) in paragraph (2)(B), by striking only . (g) Licensing of ammunition dealers (1) In general Section 923(a) of title 18, United States Code, is amended in the matter preceding paragraph (1), by striking , or importing or manufacturing and inserting or . (2) Definitions Section 921(a) of title 18, United States Code is amended— (A) in paragraph (11)(A), by inserting or ammunition after firearms ; (B) in paragraph (12), by inserting or ammunition after any firearm ; and (C) in paragraph (13), by inserting or ammunition after firearms . 5. Armor-piercing and incendiary ammunition (a) Expanding definition of armor-Piercing bullets Section 921(a)(17)(B) of title 18, United States Code, is amended— (1) in clause (i), by striking or at the end; (2) in clause (ii), by striking the period at the end and inserting ; or