Missouri Revised Statutes Title XXXVIII. Crimes and Punishment; Peace Officers and Public Defenders § 571.014. Unlawful refusal to transfer by denying sale of a firearm to a nonlicensee, crime of--violation, penalty--inapplicability, when

1. A person commits the crime of unlawful refusal to transfer by denying sale of a firearm to a nonlicensee, who is otherwise not prohibited from possessing a firearm under state or federal law, solely on the basis that the nonlicensee purchased a firearm that was later the subject of a trace request by law enforcement.

2. Violation of subsection 1 of this section shall be a class A misdemeanor.

3. Notwithstanding any other provision of law to the contrary, no federal firearms dealer licensed under 18 U.S.C. Section 923 who engages in the sale of firearms within this state shall fail or refuse to complete the sale of a firearm to a customer in every case in which the sale is authorized by federal law.

4. The provisions of this section shall not apply to any individual federal firearms license holder, his agents, or employees to the extent they chose in their individual judgment to not complete the sale or transfer of a firearm for articulable reasons specific to that transaction, so long as those reasons are not based on the race, gender, religion, creed of the buyer.