Colorado magazine capacity law: the 15-round limit
Last verified against primary sources: · Updated
Colorado limits magazine capacity to 15 rounds. Under C.R.S. § 18-12-301, a "large-capacity magazine" is one that accepts, or can be readily converted to accept, more than 15 rounds. Since July 1, 2013 it has been unlawful to sell, transfer, or possess such a magazine (C.R.S. § 18-12-302) — now a class 1 misdemeanor after SB25-003 raised the penalty on April 10, 2025.
Two things stay legal: buying and owning any magazine holding 15 rounds or fewer, and keeping a large-capacity magazine you owned before July 1, 2013 and have held continuously since (the "grandfather" rule). This is separate from the August 1, 2026 law, which regulates certain firearms, not magazines.
What counts as a "large-capacity magazine"
Colorado's magazine rule turns on a single definition in C.R.S. § 18-12-301. The threshold is more than 15 rounds, with separate, higher figures for shotgun magazines and specific carve-outs for permanently altered, .22 rimfire, and lever-action tubular magazines:
(2)(a) 'Large-capacity magazine' means: (I) 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 fifteen rounds of ammunition; (II) A fixed, tubular shotgun magazine that holds more than twenty-eight inches of shotgun shells, including any extension device that is attached to the magazine and holds additional shotgun shells; or (III) 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. (b) 'Large-capacity magazine' does not mean: (I) A feeding device that has been permanently altered so that it cannot accommodate more than fifteen rounds of ammunition; (II) An attached tubular device designed to accept, and capable of operating only with, .22 caliber rimfire ammunition; or (III) A tubular magazine that is contained in a lever-action firearm.
Key points from the text: the line is more than fifteen rounds, so a 15-round magazine is legal and a 16-round magazine is not. A magazine "designed to be readily converted" to exceed 15 rounds also counts. A magazine permanently altered so it can never hold more than 15 rounds is expressly outside the definition, as are .22-caliber rimfire tubular devices and lever-action tubular magazines.
The prohibition: sell, transfer, or possess
Section 18-12-302 makes it a crime to sell, transfer, or possess a large-capacity magazine. Note that the operative verbs include possess — not just commercial sale:
Except as otherwise provided in this section, a person who sells, transfers, or possesses a large-capacity magazine commits a class 1 misdemeanor.
Most sites have the penalty wrong. The base offense is now a class 1 misdemeanor, not a class 2. SB25-003 raised it in Section 8 of the act, and that change took effect April 10, 2025 — the day the Governor signed the bill — not on the August 1, 2026 date that applies to the separate firearm-purchase rules. Pages that still say "class 2 misdemeanor" are describing pre-April-2025 law. Possessing a large-capacity magazine during a felony or crime of violence is a class 6 felony (§ 18-12-302(1)(c)).
The grandfather clause
You can lawfully keep a large-capacity magazine if you owned it before the ban took effect and have never let it out of your continuous possession. The statute also puts the burden of disproving that defense on the prosecution — a detail written into the statute itself, not just case law:
(2)(a) A person may possess a large-capacity magazine if he or she: (I) Owns the large-capacity magazine on July 1, 2013; and (II) Maintains continuous possession of the large-capacity magazine. (b) If a person who is alleged to have violated subsection (1) of this section asserts that he or she is permitted to legally possess a large-capacity magazine pursuant to paragraph (a) of this subsection (2), the prosecution has the burden of proof to refute the assertion.
Both conditions must hold: ownership on July 1, 2013 and unbroken possession since. There are also narrow exceptions in § 18-12-302(3) for licensed manufacturers and dealers selling to the armed forces, government agencies, out-of-state buyers, or approved foreign governments, and for on-duty government and military personnel.
What is legal today
| Scenario | Status | Basis |
|---|---|---|
| Buying or possessing a magazine holding 15 rounds or fewer | Legal — no state restriction | § 18-12-301(2)(a)(I) |
| Possessing a large-capacity magazine owned before July 1, 2013 and kept in continuous possession since | Legal (grandfathered) | § 18-12-302(2)(a) |
| Bringing a large-capacity magazine into Colorado from out of state and keeping it here | Illegal — the statute bans "possesses," and there is no "brought from another state" exception | § 18-12-302(1)(a), (2), (3) |
| Selling, transferring, or possessing a large-capacity magazine without an exception | Class 1 misdemeanor (class 6 felony if during a felony/crime of violence) | § 18-12-302(1)(a),(c) |
The out-of-state point catches people off guard. Because the ban reaches mere possession, a magazine that was perfectly legal where you bought it becomes unlawful to keep once you and it are in Colorado, unless you independently qualify for the pre-2013 grandfather rule or one of the § 18-12-302(3) exceptions.
Manufacturer marking requirement
A separate section, § 18-12-303, requires large-capacity magazines made in Colorado on or after July 1, 2013 to be permanently marked. It remains in force and was not amended by SB25-003:
A large-capacity magazine that is manufactured in Colorado on or 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.
Manufacturing a magazine in violation of the marking rule is a class 2 misdemeanor (§ 18-12-303(3)).
How this relates to the August 1, 2026 law
SB25-003 gets a lot of attention, but it does not change the 15-round threshold or repeal §§ 18-12-301 or 18-12-302. Instead it adds a new, separate statute — C.R.S. § 18-12-116 — whose own codified heading frames it as an enforcement tool for the existing magazine ban by regulating certain firearms rather than the magazines themselves:
Enforcement of large-capacity magazine ban by regulating the manufacture, distribution, transfer, sale, and purchase of specified semiautomatic firearms - penalties - definitions.
From August 1, 2026, § 18-12-116 restricts the manufacture, distribution, transfer, sale, and purchase of "specified semiautomatic firearms" — broadly, semiautomatic rifles and shotguns with a detachable magazine and gas-operated semiautomatic handguns with a detachable magazine. It bans building or selling those firearms, not the magazines, and it does not criminalize merely possessing one you already own. The full breakdown is on our August 1, 2026 gun law page. The magazine rules on this page are already in force today and are unaffected by that date.
Local rules: Denver and Boulder
Denver matches the state 15-round line
A common claim online is that "Denver's limit is 10 rounds." That is out of date. Denver amended its ordinance in 2018 specifically to track the state's 15-round threshold — it had previously used a more permissive 21-round figure:
Specific magazine prohibited. It shall be unlawful to carry, store or otherwise possess a magazine which will hold or may be modified to hold more than fifteen (15) rounds, except that this subsection shall not apply to: (1) Any federal, state or local government agency or to any sworn members of said agencies acting within their official capacities. (2) Any magazine which is being used as a movie prop...
So Denver's magazine ceiling is the same 15 rounds as the rest of Colorado. Violations carry a fine of $100 to $999 and 10 to 180 days of incarceration (§ 38-130).
Boulder has a 10-round ordinance, but enforcement is paused
Boulder is different. After the 2021 repeal of Colorado's firearms-preemption statute, Boulder re-enacted ordinances that, among other things, ban magazines holding more than 10 rounds (Boulder Revised Code § 5-8-28 and related Title 5, Chapter 8 sections). But according to the City of Boulder's own page, the city has paused enforcement of that ban pending litigation:
Per the City of Boulder's official gun-violence-prevention page: "The ban on assault weapons and large-capacity magazines has been paused to allow for more legal coordination. All other measures, including the ban on trigger activators, remain in effect." The pause is tied to Rocky Mountain Gun Owners v. Town of Superior (D. Colo.), in which a federal judge issued a July 17, 2025 order letting challenges to Boulder's and Boulder County's large-capacity-magazine and assault-weapons provisions proceed. As of our July 20, 2026 check, the case was unresolved and the pause was still the operative posture. We could not verify the exact codified text of Boulder's § 5-8-28 against a primary Boulder source, so we do not quote its 10-round provision verbatim — the 10-round figure and the enforcement pause come from the city's own program page. This status can change; confirm the current posture with the city before relying on it.
Is the state ban being challenged?
The state 15-round ban has already survived its constitutional challenge. In Rocky Mountain Gun Owners v. Polis, 2020 CO 66, 467 P.3d 314, the Colorado Supreme Court unanimously upheld §§ 18-12-301, 18-12-302, and 18-12-303 under the Colorado Constitution's right-to-bear-arms provision, holding that "limiting magazine size to fifteen rounds of ammunition does not unreasonably burden the right to self-defense." No injunction is in place; the state magazine ban is in force today.
Common questions
What is the magazine limit in Colorado?
Fifteen rounds. A magazine that accepts, or can be readily converted to accept, more than 15 rounds is a "large-capacity magazine" under C.R.S. § 18-12-301 and is unlawful to sell, transfer, or possess in Colorado, subject to a grandfather clause for magazines owned before July 1, 2013.
Is Denver’s magazine limit 10 or 15 rounds?
15 rounds. Denver amended D.R.M.C. § 38-130(i) in 2018 to match the state's more-than-15-rounds threshold, replacing an older 21-round figure. The widely repeated "Denver is 10 rounds" claim is incorrect; Boulder — not Denver — is the city with a 10-round ordinance.
Can I keep a magazine I owned before the ban?
Yes, if you owned it on July 1, 2013 and have kept it in continuous possession ever since (C.R.S. § 18-12-302(2)(a)). If you raise that grandfather defense, the prosecution carries the burden of disproving it. Both conditions must be met — pre-2013 ownership and unbroken possession.
What is the penalty for a large-capacity magazine in Colorado?
Selling, transferring, or possessing a large-capacity magazine is a class 1 misdemeanor. SB25-003 raised it from a class 2 misdemeanor effective April 10, 2025. Possessing one during a felony or crime of violence is a class 6 felony (C.R.S. § 18-12-302(1)(c)).
Can I bring a high-capacity magazine into Colorado from another state?
No, not lawfully. Section 18-12-302 bans possessing a large-capacity magazine, and there is no exception for magazines brought in from out of state. Once it is in your possession in Colorado it is unlawful unless you separately qualify for the pre-2013 grandfather rule or an enumerated § 18-12-302(3) exception.
Does the August 1, 2026 law change the magazine limit?
No. SB25-003 leaves the 15-round threshold and §§ 18-12-301–302 intact. It adds a separate statute, C.R.S. § 18-12-116, that from August 1, 2026 regulates the sale and purchase of certain semiautomatic firearms with detachable magazines — not the magazines themselves. See our August 1, 2026 page for details.
Primary sources for this page
- C.R.S. § 18-12-301 — Colorado Bureau of Investigation (C.R.S. mirror, PDF)
- C.R.S. § 18-12-302 — Justia (2025 Colorado Revised Statutes)
- C.R.S. § 18-12-303 — Colorado Bureau of Investigation (C.R.S. mirror, PDF)
- SB25-003 enrolled act (PDF) — Colorado General Assembly
- D.R.M.C. § 38-130 signed ordinance (CB17-1400) — City and County of Denver
- Gun violence prevention ordinances — City of Boulder
- Rocky Mountain Gun Owners v. Polis, 2020 CO 66 — Justia (case mirror)