Along with the rapid-fire device definition change we cover in Rapid Fire Devices, SB25-003 also adds a definition of "semiautomatic firearm" to C.R.S. 18-12-101. This is the part of the bill that affects the largest number of Colorado gun owners.

Here's the new definition in full:

"Semiautomatic firearm" means a firearm that is not a machine gun and that, upon initiating the firing sequence, fires the first chambered cartridge and uses a portion of the energy of the firing cartridge to extract the expended cartridge case, chamber the next round, and prepare the firing mechanism to fire again, and requires a separate pull, release, push, or initiation of the trigger to fire each cartridge. "Semiautomatic firearm" includes a semiautomatic rifle, semiautomatic shotgun, or semiautomatic handgun.

Reading that, it's hard to see how any modern firearm avoids this label other than bolt-, pump-, lever-, or slide-action guns. On its own, though, this definition doesn't ban anything — it just sets up the term used in the next new section.

18-12-116: the actual restriction

SB25-003 adds C.R.S. 18-12-116, titled "Enforcement of large-capacity magazine ban by regulating the manufacture, distribution, transfer, sale, and purchase of specified semiautomatic firearms." This is the section that regulates manufacture, distribution, transfer, sale, and purchase of a "specified semiautomatic firearm" (SSF), and it's where the penalties live.

The operative line:

On or after August 1, 2026, it is unlawful for any person to knowingly manufacture, distribute, transfer, sell, or purchase a specified semiautomatic firearm, except that a person may sell or transfer a specified semiautomatic firearm to an individual residing in another state or a federally licensed firearms dealer (FFL).

A first-time violation is a class 2 misdemeanor; a second or subsequent violation is a class 6 felony. A conviction also carries downstream consequences: it becomes a disqualifying prior offense under Colorado's felon/prohibited-person statute (18-12-108), it's a ground for the state to deny a future firearm transfer through the background check system for five years, and it can be grounds to revoke a state firearms dealer permit.

Important nuance the "unlawful to purchase" language obscures: this is not a flat ban on individuals buying SSFs. Subsection (3) carves out several categories, and one of them applies to ordinary private citizens: a person who obtains a Firearms Safety Course Eligibility Card (which requires a name-based background check through their county sheriff) and completes a state-approved firearms safety course can still lawfully purchase or receive an SSF. In practice, Colorado Parks and Wildlife runs this as the "Firearms Safety Program" — apply through the Firearms Safety System, pass a background check with your sheriff's office, then complete either a 4-hour Basic course (if you've also completed hunter education) or a 12-hour Extended course, pass a 90%-or-better exam, and you're eligible to buy SSFs for five years. There are also standalone exceptions for law enforcement, the Department of Corrections, the National Guard/armed services, armored-vehicle businesses, licensed gunsmiths and gunsmithing students, museums (firearm must be rendered inoperable), forensic labs, estate transfers, and film props — worth reading in full if any of those apply to you.

Definitions that matter

  • "Cycle the action" means to extract the fired cartridge case, chamber the next cartridge, and prepare the firing mechanism to fire again — essentially, what every semiautomatic firearm does on every shot.
  • "Detachable magazine" means an ammunition feeding device that isn't permanently attached to the firearm and can be removed without leaving the firearm unable to accept any magazine. It excludes an attached tubular magazine under the barrel. That carve-out isn't shotgun-specific — it covers any semiautomatic rifle or shotgun built with a fixed, non-detachable tubular magazine.
  • "Gas-operated semiautomatic handgun" means a semiautomatic handgun that harnesses or traps high-pressure gas from a fired cartridge to cycle the action, using one of five specified methods: a long-stroke piston, a short-stroke piston, direct gas impingement on the bolt/carrier/slide, a hybrid of those systems, or straight blowback operation.

So what's a "specified semiautomatic firearm"?

18-12-116 defines an SSF as either: a semiautomatic rifle or semiautomatic shotgun with a detachable magazine, or a gas-operated semiautomatic handgun with a detachable magazine.

Read in isolation, that still sounds like it covers most modern rifles and shotguns. But the same subsection lists a series of carve-outs, and they matter:

  • Firearms that accept only .22-or-lower-caliber rimfire ammunition — unless the firearm has a separate upper and lower receiver. (A .22 AR-platform rifle or pistol loses the rimfire exemption because of that separate-receiver design and would still be an SSF.)
  • Firearms manually operated by bolt, pump, lever, or slide action.
  • Firearms with a permanently fixed magazine that can't hold more than 15 rounds, including a semiautomatic firearm that's been converted to a fixed 15-round-or-fewer magazine.
  • A single- or double-action semiautomatic handgun that uses recoil (not gas) to cycle the action. This is the exception that keeps most conventional pistols — your typical Glock, 1911, or similar recoil-operated design — out of SSF territory. It's also the reason an AR-pattern pistol, which cycles by gas rather than recoil, would still be classified as an SSF if it has a detachable magazine.
  • A firearm that's been made permanently inoperable, or that qualifies as an antique or a curio/relic under federal law.
  • A named list of roughly 30 specific legacy semiautomatic rifle models, exempted by name regardless of magazine type — as they existed and were configured on the bill's effective date. Examples include the M1 Carbine, Ruger Mini-14 and Mini Thirty, several Remington Model 740/742/750/7400 variants, the Browning BAR (and BAR Longtrac/Shorttrac), HK SL6/SL7, and a number of older foreign-military-surplus rifles (FN49, Hakim, MAS49, SVT-40, and others). If you own one of these specific models, it's exempt outright — check the bill text for the complete list.

Guidance still to come

Because these definitions leave real room for interpretation, the bill also adds C.R.S. 24-35-122, "Specified semiautomatic firearms guidance." It directs the division within the Department of Revenue that issues state firearms dealer permits to publish guidance clarifying which specific firearm models qualify as SSFs, consulting with firearms experts and industry/public stakeholders as needed. The statute itself doesn't set a hard publication deadline, but since the law takes effect August 1, 2026, the division will need that list out well before then for dealers and buyers to actually rely on it. We'll update this post once it's published.

Bottom line: almost every detachable-magazine semiautomatic rifle and shotgun, plus gas-operated semiautomatic handguns, will be treated as an SSF starting August 1, 2026 — with the exceptions above (rimfire-only guns without separate receivers, manual actions, fixed low-capacity magazines, recoil-operated handguns, antiques, and the named legacy rifle list). After that date, manufacture, distribution, sale, transfer, and purchase of an SSF is restricted to the carved-out categories — including private buyers who complete the state's background-check-and-safety-course process.