Colorado Revised Statutes Title 18. Criminal Code § 18-12-402. Retail dealers--record--inspection

Every individual, firm, or corporation engaged, within this state, in the retail sale, rental, or exchange of firearms, pistols, or revolvers shall keep a record of each pistol or revolver sold, rented, or exchanged at retail. The record must be made at the time of the transaction in a book kept for that purpose and must include the name of the person to whom the pistol or revolver is sold or rented or with whom exchanged; his or her age, occupation, residence, and, if residing in a city, the street and number therein where he or she resides; the make, caliber, and finish of said pistol or revolver, together with its number and serial letter, if any; the date of the sale, rental, or exchange of said pistol or revolver; and the name of the employee or other person making such sale, rental, or exchange. The record book shall be open at all times to the inspection of any duly authorized police officer.