No. Although Colorado gun laws allow for open and concealed carry, it is illegal to own a gun if you have a Colorado medical marijuana card. Currently, the state abides by federal law prohibiting persons using marijuana from obtaining firearms.
Per Colorado law, a sheriff may not issue a permit to an individual to own a gun if the individual is not eligible to possess a firearm under federal law. According to 18 USC 922 (g)(3), anyone who is an unlawful user of or addicted to a controlled substance, such as marijuana, may not own or possess firearms or ammunition. There are no exceptions in federal law for marijuana consumers using the drug for medical purposes. Hence, a MMJ patient in Colorado cannot obtain a permit to possess a gun.
Note that under federal law, any individual who uses marijuana, regardless of whether the state in which consumption occurs has passed legislation authorizing marijuana use for medicinal purposes, is considered an unlawful user.
Although Colorado does not allow MMJ patients to purchase or possess guns, the state requires anyone purchasing firearms to undergo background checks. To promote gun safety in the state, the Firearms InstaCheck Unit of the Colorado Bureau of Investigation performs comprehensive background investigations into each and every firearm purchase.
You may be successful in your application for a Colorado medical marijuana card even though you possess a gun license. However, if caught, you risk severe penalties under federal law. Once your medical marijuana card expires, you can apply to obtain a gun permit if you meet the other conditions required under Colorado gun laws. Also, nothing in the state's laws prohibits the spouse of an MMJ patient from obtaining a gun license. Hence, your spouse, who is not an MMJ patient, can get a gun license while you remain a medical marijuana patient under the state’s medical marijuana program.
In recent years, Colorado lawmakers made a move to allow medical marijuana patients to apply for gun permits legally. In 2019, Colorado legislators introduced a bill (SB19-093) that proposed to lift the prohibition on carrying firearms for persons with prior convictions for marijuana possession or use. Also, the bill proposed that an individual may not be prohibited from possessing a firearm pursuant to federal law or considered to be an unlawful user of a controlled substance because of the use or possession of medical marijuana pursuant to the Colorado Constitution.
Furthermore, SB19-093 proposed to restrict the Colorado Department of Public Safety from sharing patients' confidential information in the Colorado medical marijuana registry with law enforcement for the purpose of carrying out background checks related to the transfer of firearms. SB19-093 ultimately failed to progress in the Colorado legislature.
Federal gun laws relating to the possession of firearms and marijuana use are strict in the United States. While the Second Amendment Protection Act guarantees the right to bear arms, the Gun Control Act of 1968 prohibits individuals who are unlawful users of or addicted to any controlled substance from possessing firearms. This includes marijuana, which remains classified as a Schedule I controlled substance under the Controlled Substances Act (CSA).
Although Colorado is not covered by the Ninth Circuit Court of Appeals, the court ruled in 2016 in the Wilson v. Lynch case that persons with medical marijuana cards may not be allowed to purchase or possess firearms.
In line with this ruling, the agency responsible for the sale and possession of firearms in the United States amended the 4473 form to require prospective gun buyers to indicate whether they are unlawful marijuana users or addicted to the substance as stated under the Gun Control Act of 1968. Medical marijuana users who acknowledge cannabis use on Form 4473 will be disqualified from purchasing guns. However, MMJ patients who answer "no" to the question about marijuana use risk perjury charges, which could result in significant legal consequences. Note that pursuant to federal law, using marijuana for medical purposes will be construed as an unlawful use of marijuana due to the illegal status of cannabis federally.