A licensee or permittee shall not knowingly distribute any explosive materials to any person who:
(a) Is not a licensee or holder of a user permit;
(b) Is not a holder of a limited permit who resides in the same state where distribution is made and in which premises of the transferor are located;
(c) The licensee has reason to believe that they intend to transport such explosive materials into a state where the purchase, possession or use of explosive materials is prohibited or which does not permit its residents to transport or ship explosive materials into the state or to receive explosive materials in the state; or,
(d) Is in any state where the purchase, possession, or use by such person of such explosive materials would be in violation of any state law or any published ordinance applicable at the place of distribution.
[18 U.S.C. 842; 27 CFR 555.105, 555.106]