Can I Build an AR-15 in Colorado?
Woody's answers are based on published federal and state law. Not legal advice. Consult a licensed attorney for your specific situation.
Yes, you can legally build an AR-15 in Colorado, but you must comply with the state's 15-round magazine capacity limit and follow federal regulations for 80% receivers if going that route.
What This Means for You
Colorado allows AR-15 builds but restricts magazine capacity to 15 rounds or less. You need to understand both state capacity restrictions and federal requirements for personal firearm manufacturing. Private sales and transfers have additional requirements in Colorado.
The Detail
Building an AR-15 in Colorado is perfectly legal under both state and federal law. The key restriction you'll face is Colorado's magazine capacity limit of 15 rounds, which applies to all magazines manufactured, imported, or sold after the law took effect in 2013. This means you can legally possess standard capacity magazines that were in the state before the ban, but you cannot legally acquire new ones.
If you're building from an 80% lower receiver, federal law allows you to manufacture a firearm for personal use without an FFL, provided you're not prohibited from owning firearms and don't intend to sell it. However, you must be able to legally possess the completed firearm. Colorado doesn't have additional state-level requirements beyond federal law for personal manufacturing, but the finished rifle must comply with all applicable laws including the magazine restriction.
Colorado requires background checks for all firearm transfers, including private sales. This means if you later decide to sell your completed build, you'll need to go through an FFL dealer for the transfer. The state also has red flag laws that could temporarily restrict your ability to possess firearms under certain circumstances.
When sourcing parts, remember that while you can legally own pre-ban magazines over 15 rounds if they were in Colorado before 2013, proving this can be difficult. Most builders simply use 15-round magazines to avoid any potential legal issues. The rifle itself has no specific configuration restrictions in Colorado beyond federal requirements.
Build Impact
You'll need to plan around the 15-round magazine limit when selecting magazines and consider this restriction for your intended use. The transfer requirements mean you should think carefully about future sales, as you'll need FFL involvement rather than simple private transfers.