Are ghost guns legal in Colorado?
Last verified against primary sources: · Updated
No — "ghost guns" (unserialized firearms, frames, and receivers) are illegal to possess, buy, sell, or transport in Colorado. Under C.R.S. § 18-12-111.5 (SB23-279), a firearm or frame or receiver must be imprinted with a serial number by a federal firearms licensee. A first offense is a class 1 misdemeanor and a second or subsequent offense is a class 5 felony. The law includes a pathway to have a pre-existing homemade firearm serialized. A separate 2026 law also bans making firearms and key components by 3-D printing as of July 1, 2026.
What Colorado prohibits
Colorado's unserialized-firearm law, § 18-12-111.5, is titled "Unlawful conduct involving an unserialized firearm, frame, or receiver." It reaches both unfinished frames or receivers and complete firearms that lack a serial number applied by a federal firearms licensee.
A person shall not knowingly possess or transport an unfinished frame or receiver; except that it is not an offense if the unfinished frame or receiver is required by federal law to be imprinted with a serial number and has been imprinted with a serial number by a federal firearms licensee pursuant to federal law or subsection (7) of this section.
A person shall not knowingly possess, purchase, transport, or receive a firearm or frame or receiver of a firearm that is not imprinted with a serial number by a federal firearms licensee authorized to imprint a serial number on a firearm, frame, or receiver pursuant to federal law or subsection (7) of this section.
The statute also bars manufacturing a frame or receiver, including by 3-D printer, except by a federally licensed manufacturer:
(I) A person shall not manufacture or cause to be manufactured, including through the use of a three-dimensional printer, a frame or receiver of a firearm. (II) This subsection (5)(a) does not apply to a federally licensed firearm manufacturer.
Exempt from the section are antique firearms (18 U.S.C. § 921(a)(16)), firearms manufactured before October 22, 1968, permanently inoperable or defaced firearms, and federally licensed importers and manufacturers acting within their license.
The serialization pathway for existing homemade guns
The law gave owners of pre-existing self-made firearms a route to legality: have the firearm serialized by a federal firearms licensee.
A person who owns, on the day before June 2, 2023, a firearm or a frame or receiver of a firearm that the person manufactured and that is not imprinted with a serial number by a federal firearms licensee shall, no later than January 1, 2024, have the firearm or the frame or receiver of a firearm imprinted with a serial number by a federal firearms licensee authorized to imprint a serial number on a firearm, frame, or receiver pursuant to federal law or subsection (7) of this section.
Under subsection (7), the licensee imprints a serial number that begins with the dealer's abbreviated FFL number, keeps records, and must run a background check before returning the newly serialized firearm to its owner.
Penalties and effective dates
Unlawful conduct involving an unserialized firearm, frame, or receiver is a class 1 misdemeanor; except that a second or subsequent offense is a class 5 felony.
The rollout came in two phases. The bans on selling, transferring, and manufacturing unserialized frames or receivers, plus the retrofit-serialization deadline, took effect June 2, 2023. The bans on possessing an unfinished frame or receiver and on possessing, purchasing, transporting, or receiving an unserialized complete firearm were delayed to January 1, 2024. A conviction under this section is also a POWPO-triggering felony predicate — see Colorado gun charges and penalties.
New for 2026: the 3-D printing ban (HB26-1144)
A separate 2026 law reaches 3-D-printed guns and components more broadly.
Effective July 1, 2026: HB26-1144 prohibits knowingly manufacturing or producing a potentially functioning firearm, an unfinished frame or receiver, a large-capacity magazine, or a rapid-fire device by 3-dimensional printing. Penalties are a class 1 misdemeanor for a first offense and a class 5 felony for a second or subsequent offense. See the bill page.
Litigation note
A challenge to Colorado's unserialized-firearm law (C.R.S. § 18-12-111.5) has been reported — a suit associated with Rocky Mountain Gun Owners. This is news-grade information, not verified against a primary court filing, and it concerns the ghost-gun statute — a different law from the August 2026 semiautomatic-firearm changes under SB25-003. As of our last check, the ghost-gun statute remains in effect. Court status can change quickly.
This page describes what the statutes say; it is not legal advice. If you own a self-made or unserialized firearm, consult a Colorado attorney or a federal firearms licensee about your options.
Common questions
Can you build your own gun in Colorado?
Only if it is serialized. Under C.R.S. § 18-12-111.5, a firearm or its frame or receiver must be imprinted with a serial number by a federal firearms licensee, and manufacturing a frame or receiver (including by 3-D printer) is prohibited except by a federally licensed manufacturer.
Are 80% lowers legal in Colorado?
No. Knowingly possessing or transporting an unfinished frame or receiver is prohibited under C.R.S. § 18-12-111.5(1)(a) unless it has been imprinted with a serial number by a federal firearms licensee.
What is the penalty for a ghost gun in Colorado?
A first offense of unlawful conduct involving an unserialized firearm, frame, or receiver is a class 1 misdemeanor; a second or subsequent offense is a class 5 felony (C.R.S. § 18-12-111.5(6)(b)).
Are 3D-printed guns legal in Colorado?
No. Beyond the existing unserialized-firearm law, HB26-1144 bans knowingly manufacturing a potentially functioning firearm, unfinished frame or receiver, large-capacity magazine, or rapid-fire device by 3-D printing, effective July 1, 2026.