SB25-003 repeals the existing "machine gun conversion device" definition in C.R.S. 18-12-101 (Peace officer affirmative defense – definitions) and replaces it with a new term: "rapid-fire device." A rapid-fire device is now any add-on device, part, kit, tool, accessory, or combination of those that increases a semiautomatic firearm's rate of fire above what that same firearm's standard rate of fire would be without the device attached. The most recognizable piece of equipment that fits this definition is a bump stock.
Why does this definition matter? Later in the bill, it's used to update C.R.S. 18-12-102 (Possessing a dangerous or illegal weapon). That section's list of "dangerous weapons" — which drives the felony level you face for possession — previously read: "a firearm silencer, machine gun, machine gun conversion device, short shotgun, or short rifle." SB25-003 swaps "machine gun conversion device" out for "rapid-fire device." Machine guns themselves stay on the list unchanged; it's specifically the conversion-device language that's been replaced with the broader rapid-fire-device term.
18-12-102 also has a long-standing affirmative defense: it's not a crime to possess one of these dangerous weapons if you're a peace officer or member of the armed forces/National Guard acting in your official duties, or if you hold "a valid permit and license for possession of such weapon." That second prong is what covers NFA items like suppressors, short-barreled rifles, and short-barreled shotguns — items you can legally own once you've gone through the ATF's registration process and paid for the associated tax stamp. Machine guns and, now, rapid-fire devices have no such path: there's no ATF registration process available for a private citizen to obtain a permit or license for either one, so the affirmative defense doesn't apply and there's no way to make possession legal.
Why lawmakers needed a new term
The old "machine gun conversion device" definition covered parts "designed or intended for use in converting a firearm into a machine gun" — think auto sears, the kind of part that makes a gun fire multiple rounds from a single pull of the trigger. A bump stock doesn't do that: it still requires the trigger to reset and be actuated separately for each shot, it just uses the gun's recoil to do that resetting very fast. That mechanical distinction is exactly what the Supreme Court's 2024 Cargill ruling turned on (more below), and it likely meant Colorado's old conversion-device definition never squarely covered bump stocks either. In practice, the state was probably leaning on the federal machine-gun ban to keep bump stocks out of Colorado. Once that federal classification went away, the state needed a definition that reached rate-of-fire enhancers directly, regardless of whether they technically convert a gun to true full-auto — hence "rapid-fire device."
The bump stock backstory
Before 2018, the ATF's position was that bump stocks were not machine guns. After the 2017 Las Vegas mass shooting, in which the gunman used bump stocks, the ATF issued a rule reinterpreting the National Firearms Act's definition of "machine gun" to include bump stocks, effectively banning them. That rule gave existing owners until March 26, 2019 to destroy their bump stocks or surrender them to an ATF office to avoid federal criminal exposure.
On June 14, 2024, the Supreme Court decided Garland v. Cargill, ruling 6–3 that a bump stock doesn't meet the statutory definition of "machine gun" under 26 U.S.C. § 5845(b) because it doesn't let a shooter fire more than one shot "by a single function of the trigger" — the trigger still resets and is pulled again for every round fired, even if that happens very fast. The ban was overturned, and bump stocks are no longer classified as machine guns under federal law. Practically, that also means bump stocks aren't NFA items, so there's no ATF tax stamp or registration process for one at the federal level.
Since bump stocks lost their federal machine-gun classification, Colorado lawmakers wrote a state-specific definition to keep them illegal here regardless of what happens federally. Under SB25-003, a bump stock is a rapid-fire device, rapid-fire devices are "dangerous weapons," and possession is a class 5 felony under 18-12-102(3) — with no tax-stamp or permit pathway to make it legal. Nothing in the bill grandfathers in bump stocks a person already owned before this change takes effect.
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