Colorado prohibits the sale, transfer and possession of a “large-capacity magazine.”1
“Large-capacity magazine” means:
- A fixed or detachable magazine, box, drum, feed strip, or similar device capable of accepting, or that is designed to be readily converted to accept, more than 15 rounds of ammunition;
- A fixed, tubular shotgun magazine that holds more than 28 inches of shotgun shells, including any extension device that is attached to the magazine and holds additional shotgun shells; or
- A nontubular, detachable magazine, box, drum, feed strip, or similar device that is capable of accepting more than eight shotgun shells when combined with a fixed magazine.2
“Large-capacity magazine” does not include:
- A feeding device that has been permanently altered so that it cannot accommodate more than fifteen rounds of ammunition;
- An attached tubular device designed to accept, and capable of operating only with .22 rimfire ammunition; or
- A tubular magazine that is contained in a lever-action firearm.3
A large-capacity magazine that is manufactured in Colorado after July 1, 2013, must include a permanent stamp or marking indicating that the large-capacity magazine was manufactured or assembled after July 1, 2013. The stamp or marking must be legibly and conspicuously engraved or cast upon the outer surface of the large-capacity magazine. The Colorado Bureau of Investigation may create rules for implementing this requirement, including additional identification information on each large-capacity magazine.4
Exceptions – A person may possess a large-capacity magazine if they owned the large-capacity magazine on or prior to July 1, 2013, and maintain continuous possession of the magazine.5 When a person charged with illegal possession of a large-capacity magazine claims to fall under this exception, the burden of proof is on the prosecution to prove otherwise.6
The large-capacity magazine ban does not apply to military or police agents that carry a firearm in the course of their official duties. The ban also does not apply to an entity or employee of an entity engaged in the manufacture of large-capacity magazines within Colorado solely for transfer to any licensed gun dealer that sells large-capacity magazines exclusively to the armed forces, government agencies, a retailer operating outside of the state of Colorado, or a foreign national government approved by the U.S. for such transfers.7
In 2025, Colorado passed Senate Bill 3, significantly strengthening the state’s existing restrictions on semi-automatic firearms. The bill amends the existing definition of “dangerous weapon” to include and thereby prohibit “rapid-fire devices,” which in turn are defined as “any device, part, kit, tool, accessory orc combination or parts that has the effect of increasing the rate of fire of a semiautomatic firearm above the standard rate of fire for the semiautomatic firearm that is not otherwise equipped with that device, part, or combination of parts.” The law’s implementation has been delayed until August 2026 to allow time for the development of necessary training programs and systems.8
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- Colo. Rev. Stat. § 18-12-302(1)(a). A violation of this prohibition will be punishable as a Class 1 misdemeanor, and it is a Class 6 felony to possess a large-capacity magazine during the commission of a felony or crime of violence. Colo. Rev. Stat. § 18-12-302(1)(a), (c).[↩]
- Colo. Rev. Stat. § 18-12-301(2)(a).[↩]
- Colo. Rev. Stat. § 18-12-301(2)(b).[↩]
- Colo. Rev. Stat. § 18-12-303.[↩]
- Colo. Rev. Stat. § 18-12-302(2)(a).[↩]
- Colo. Rev. Stat. § 18-12-302(2)(b).[↩]
- Colo. Rev. Stat. § 18-12-302(3).[↩]
- CO SB 3 (2025).[↩]