1. (1) As used in this article 12, unless the context otherwise requires:

   1. (a) Adult means any person eighteen years of age or older.

   2. (a.2) [Editor's note: Subsection (1)(a.2) is effective July 1, 2026.] Ammunition means an ammunition or cartridge case, primer, bullet, or propellant powder designed for use in a firearm. The term ammunition does not include:

      1. (I) A shotgun shot or pellet not designed for use as the single, complete projectile load for one shotgun hull or casing; or
      2. (II) An unloaded, nonmetallic shotgun hull or casing that does not have a primer.
      3. (b) Ballistic knife means any knife that has a blade that is forcefully projected from the handle by means of a spring-loaded device or explosive charge.
      4. (c) Blackjack includes any billy, sand club, sandbag, or other hand-operated striking weapon consisting, at the striking end, of an encased piece of lead or other heavy substance and, at the handle end, a strap or springy shaft that increases the force of impact.
      5. (d) Bomb means any explosive or incendiary device or molotov cocktail, as defined in section 9-7-103, or any chemical device that causes or can cause an explosion, that is not specifically designed for lawful and legitimate use in the hands of its possessor.
      6. (e) Bureau means the Colorado bureau of investigation created in section 24-33.5-401.
      7. (f) Federal firearms licensee means a federally licensed firearm dealer, federally licensed firearm importer, and federally licensed firearm manufacturer.
      8. (g) Federally licensed firearm dealer means a licensed dealer as defined in 18 U.S.C. sec. 921 (a)(11).
      9. (h) Federally licensed firearm importer means a licensed importer as defined in 18 U.S.C. sec. 921 (a)(9).
      10. (i) Federally licensed firearm manufacturer means a licensed manufacturer as defined in 18 U.S.C. sec. 921 (a)(10).
      11. (j) Firearm means any weapon, including a starter gun, that can, is designed to, or may readily be converted to expel a projectile by the action of an explosive; the frame or receiver of a firearm; or a firearm silencer. Firearm does not include an antique firearm, as defined in 18 U.S.C. sec. 921 (a)(16). In the case of a licensed collector, firearm means only curios and relics. Firearm includes a weapons parts kit that is designed to or may readily be completed, assembled, restored, or otherwise converted to expel a projectile by the action of an explosive. Firearm does not include a weapon, including a weapons parts kit, in which the frame or receiver of the firearm, as defined in subsection (1)(m) of this section, or the weapon, is destroyed.
      12. (k) Firearm silencer means any instrument, attachment, weapon, or appliance for causing the firing of any gun, revolver, pistol, or other firearm to be silent or intended to lessen or muffle the noise of the firing of any such weapon.
      13. (l) Fire control component means a component necessary for the firearm to initiate, complete, or continue the firing sequence, including any of the following: Hammer, bolt, bolt carrier, breechblock, cylinder, trigger mechanism, firing pin, striker, or slide rails.
      14. (m) Frame or receiver of a firearm means a part of a firearm that, when the complete firearm is assembled, is visible from the exterior and provides housing or a structure designed to hold or integrate one or more fire control components, even if pins or other attachments are required to connect the fire control components. Any part of a firearm imprinted with a serial number is presumed to be a frame or receiver of a firearm, unless the federal bureau of alcohol, tobacco, firearms, and explosives makes an official determination otherwise or there is other reliable evidence to the contrary.
      15. (n) Gas gun means a device designed for projecting gas-filled projectiles that release their contents after having been projected from the device and includes projectiles designed for use in such a device.
      16. (o) Handgun means a pistol, revolver, or other firearm of any description, loaded or unloaded, from which any shot, bullet, or other missile can be discharged, the length of the barrel of which, not including any revolving, detachable, or magazine breech, does not exceed twelve inches.
      17. (p) Juvenile means any person under the age of eighteen years.
      18. (q) Knife means any dagger, dirk, knife, or stiletto with a blade over three and one-half inches in length, or any other dangerous instrument capable of inflicting cutting, stabbing, or tearing wounds, but does not include a hunting or fishing knife carried for sports use. The issue that a knife is a hunting or fishing knife must be raised as an affirmative defense.
      19. (r) Locking device means a device that prohibits the operation or discharge of a firearm and that can only be disabled with the use of a key, combination, or biometric data.
      20. (s) Machine gun means any firearm, whatever its size and usual designation, that shoots automatically more than one shot, without manual reloading, by a single function of the trigger.
      21. (t) Repealed.
      22. (u) Personalized firearm means a firearm that has, as part of its original manufacture, incorporated design technology that allows the firearm to be fired only by the authorized user and prevents any of the safety characteristics of the firearm from being readily deactivated by anyone other than the authorized user. The technology limiting the firearm's operational use may include, but is not limited to, fingerprint verification, magnetic encoding, radio frequency tagging, and other automatic user identification systems utilizing biometric, mechanical, or electronic systems.
      23. (u.3) Rapid-fire device means any device, part, kit, tool, accessory, or combination of 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.
      24. (u.7) 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.
      25. (v) Short rifle means a rifle having a barrel less than sixteen inches long or an overall length of less than twenty-six inches.
      26. (w) Short shotgun means a shotgun having a barrel or barrels less than eighteen inches long or an overall length of less than twenty-six inches.
      27. (x) Stun gun means a device capable of temporarily immobilizing a person by the infliction of an electrical charge.
      28. (y) Three-dimensional printer or 3-D printer means a computer-aided manufacturing device capable of producing a three-dimensional object from a three-dimensional digital model through an additive manufacturing process that involves the layering of two-dimensional cross sections formed of a resin or similar material that are fused together to form a three-dimensional object.
      29. (z) Unfinished frame or receiver means any forging, casting, printing, extrusion, machined body, or similar article that has reached a stage in manufacture when it may readily be completed, assembled, or converted to be used as the frame or receiver of a functional firearm; or that is marketed or sold to the public to become or be used as the frame or receiver of a functional firearm once completed, assembled, or converted.
2. (2) It shall be an affirmative defense to any provision of this article that the act was committed by a peace officer in the lawful discharge of his duties.

Source: L. 71: R&RE, p. 481, § 1. C.R.S. 1963: § 40-12-101. L. 73: p. 540, § 12. L. 87: (1)(a) R&RE and (1)(a.5) and (1)(i.5) added, p. 674, §§ 1, 2, effective May 16. L. 91: (1)(b) amended, p. 407, § 17, effective June 6. L. 93, 1st Ex. Sess.: (1)(a) amended and (1)(a.3), (1)(e.5), and (1)(e.7) added, p. 1, § 1, effective September 13. L. 2007: (1)(e) amended, p. 1688, § 6, effective July 1. L. 2013: (1)(b.5) added, (HB 13-1229), ch. 47, p. 137, § 6, effective March 20. L. 2017: IP(1) amended and (1)(e) and (1)(j) repealed, (SB 17-008), ch. 74, p. 234, § 1, effective August 9. L. 2021: (1)(f.5) and (1)(g.5) added, (HB 21-1106), ch. 39, p. 146, § 3, effective July 1. L. 2023: (1)(b.4), (1)(b.6), (1)(b.8), (1)(b.9), (1)(c.3), (1)(c.5), (1)(g.2), (1)(k), and (1)(l) added, (SB 23-279), ch. 311, p. 1893, § 1, effective June 2; (1)(b.7) and (1)(c.5) added, (SB 23-169), ch. 123, p. 458, § 1, effective August 7. L. 2025: (1)(g.2) repealed and (1)(g.7) and (1)(g.8) added, (SB 25-003), ch. 68, p. 288, § 1, effective April 10; (1) amended, (SB 25-300), ch. 428, p. 2443, § 17, effective August 6; (1)(a.2) added, (HB 25-1133), ch. 89, p. 368, § 1, effective July 1, 2026.

Editor's note: (1) Amendments to subsection (1)(c.5) by SB 23-169 and SB 23-279 were harmonized.

(2) Amendments to subsection (1) by SB 25-300 and HB 25-1133 were harmonized, effective July 1, 2026.

(3) Amendments to subsection (1) by SB 25-003 and SB 25-300 were harmonized resulting in the relocation of subsection (1)(g.2), as repealed by SB 25-003, to (1)(t) and subsections (1)(g.7) and (1)(g.8), as added by SB 25-003, to (1)(u.3) nd (1)(u.7), respectively.

Cross references: (1) For affirmative defenses generally, see §§ 18-1-407, 18-1-710, and 18-1-805.

(2) For the short title (Promoting Child Safety Through Responsible Firearm Storage Act) and the legislative declaration in HB 21-1106, see sections 1 and 2 of chapter 39, Session Laws of Colorado 2021.