This rule predates SB25-003 by more than a decade, but it remains one of the most common questions we see—especially from people who moved here after it took effect. Colorado generally restricts magazines over the statutory capacity limit, while preserving a narrow exception tied to ownership on July 1, 2013 and continuous possession after that date.
The law itself
Colorado's magazine cap has been in effect since July 1, 2013 — passed in the aftermath of the 2012 Aurora theater shooting, more than a decade before anyone was talking about SB25-003. It's codified at C.R.S. 18-12-302, with the actual definition of what counts sitting one section earlier at C.R.S. 18-12-301(2)(a):
"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."
Note that phrase "designed to be readily converted to accept" — this isn't just about magazines that currently hold more than 15 rounds. A magazine built to be easily modified past that number counts too, even if it ships from the factory with an internal block or plug limiting it to 15.
Selling, transferring, or possessing a large-capacity magazine in violation of the statute is a class 1 misdemeanor. It becomes a class 6 felony if the person possessed one during the commission of a felony or crime of violence.
The cap applies the same way to rifles, shotguns, and handguns — there's no separate, more permissive number for pistol magazines. There are narrow carve-outs for military and law enforcement magazines manufactured or sold specifically to government agencies, but nothing for ordinary civilian purchasers beyond the grandfather clause below.
Two categories are excluded from the definition entirely, not just exempted from the ban: tubular .22 rimfire magazines, and tubular magazines built into lever-action firearms. If your magazine falls into either of those categories, the capacity limit never applied to it in the first place.
The grandfather clause, precisely
C.R.S. 18-12-302(2)(a) lets you keep a large-capacity magazine if — and only if — you:
1. Owned it on July 1, 2013, and 2. Have maintained continuous possession of it since then.
Both conditions matter. The text requires ownership on a specific date and continuous possession afterward. It does not expressly say the owner had to be a Colorado resident or that the magazine had to be physically located in Colorado on July 1, 2013. We have not found a controlling Colorado appellate decision resolving how that language applies to someone who owned a magazine elsewhere on the grandfather date and later moved to Colorado. That is an edge case the statutory text alone does not answer confidently.
There is also an evidentiary rule worth knowing: once a person asserts that the grandfather clause permits possession, the statute places the burden on the prosecution to refute that assertion. That does not eliminate disputes over ownership or continuous possession, but it matters to how the exception is litigated.
What this doesn't cover
This has nothing to do with SB25-003, the "specified semiautomatic firearm" list, or eligibility cards—a magazine's capacity and a firearm's SSF status are separate questions, and a firearm can implicate one, both, or neither. We've discussed fixed 15-round conversions and separately covered considerations when moving to Colorado with an AR-15. This article focuses on the statute and the grandfather date relevant to magazine possession.
Bottom line
The statutory test is ownership on July 1, 2013 and continuous possession afterward. A later purchase does not qualify merely because the magazine itself was manufactured before 2013. For someone who owned a magazine outside Colorado on the grandfather date and later moved here, the statute does not expressly provide a residency or in-state-location rule; that unresolved application deserves advice from a qualified Colorado attorney rather than a categorical internet answer.
As always, we are not lawyers—just Colorado citizens trying to understand the rules, statutes, and court decisions and share what we learn. The information on this website is for general informational purposes only and does not constitute legal advice, nor does it create an attorney/client relationship. The accuracy, completeness, or currency of the content is not warranted. Your use of content on this website is at your own risk. Consult an attorney about your specific circumstances.
