C.R.S. § 18-12-115

(1) Intentionally left blank —Ed. (a) It is unlawful for any person who sells a firearm, including a licensed gun dealer as defined in section 18-12-506 (6), to deliver the firearm to the purchaser until the later in time occurs: (I) Three days after a licensed gun dealer has initiated a background check of the purchaser that is required pursuant to state or federal law; or (II) The seller has obtained approval for the firearm transfer from the bureau after it has completed any background check required by state or federal law. (b) A person who violates this subsection (1) commits a civil infraction and, upon conviction thereof, shall be punished by a fine of five hundred dollars; except that for a second or subsequent offense, the fine shall be not less than five hundred dollars and not more than five thousand dollars. (2) This section does not apply to: (a) The sale of an antique firearm, as defined in 18 U.S.C. sec. 921 (a)(16), as amended, or a curio or relic, as defined in 27 CFR 478.11, as amended; (b) The sale of a firearm by a person serving in the armed forces of the United States who will be deployed outside of the United States within the next thirty days to any family member, including: (I) Regardless of age, a biological, adopted, or foster child; a stepchild or legal ward; a child of a domestic partner; a child to whom the seller stands in loco parentis; or a person to whom the seller stood in loco parentis when the person was a minor; (II) A biological, adoptive, or foster parent; a stepparent or legal guardian of the seller or seller’s spouse or domestic partner; or a person who stood in loco parentis when the seller or seller’s spouse or domestic partner was a minor child; (III) A person to whom the seller is legally married under the laws of any state or a domestic partner of a seller; (IV) A grandparent, grandchild, or sibling, whether a biological, foster, adoptive, or step relationship, of the seller or seller’s spouse or domestic partner; or (V) As shown by the seller, any other individual with whom the seller has a significant personal bond that is or is like a family relationship, regardless of biological or legal relationship; or (c) A firearm transfer for which a background check is not required pursuant to state or federal law. (3) Pursuant to the authority granted in section 29-11.7-103 , a local government may enact an ordinance, regulation, or other law concerning a waiting period.