Unlocking the Potential of 80% Lowers: A Guide to Building Your Firearm

In recent years, “80% lowers” have garnered significant attention among firearm enthusiasts, particularly in the United States. For many, 80% lower receivers represent an accessible way to build a custom firearm legally and affordably. This blog explores what 80% lowers are, why they’re popular, the legal considerations involved, and how to approach the process of building a firearm from scratch.

What Are 80% Lowers?

An “80% lower” refers to a firearm receiver that is partially completed—about 80% of the way through the manufacturing process. It lacks certain features, such as the fire control group cavity, that would otherwise classify it as a fully functioning firearm. Because these parts are not complete, they aren’t considered firearms by federal regulations and can be purchased without a background check in most states.

The term “lower” specifically refers to the lower receiver on a firearm, particularly for AR-15-style rifles. In this context, the lower receiver is the essential part of the firearm that houses the trigger group and magazine. Completing the lower receiver with a few additional steps enables gun owners to turn this part into a fully functioning firearm legally, provided they comply with relevant laws.

Why Are 80% Lowers So Popular?

1. Legal Accessibility: The primary appeal of 80% lowers is the legal freedom they offer. Since they aren’t technically classified as firearms, anyone in the U.S. (in states where it’s legal) can purchase an 80% lower without undergoing the background checks typically required for firearm purchases. This makes 80% lowers especially attractive to hobbyists and those who value privacy.
2. Customization: Building a firearm from an 80% lower gives gun owners full control over the customization process. Many enthusiasts appreciate the ability to choose their components, from triggers to barrels to stocks, creating a firearm tailored precisely to their preferences.
3. Learning Opportunity: For many, completing an 80% lower serves as an educational experience. Hobbyists enjoy learning the mechanics of firearm operation and assembly, making it an engaging project that enhances their knowledge and skills in the area.
4. Cost Savings: Building a firearm from scratch using an 80% lower can often be less expensive than buying a complete, pre-built firearm. While it requires the purchase of additional tools and components, these expenses are often offset by savings in the long run.

Understanding the Legal Considerations

While 80% lowers are legally distinct from firearms at the federal level, state regulations vary widely. Here are some legal points to keep in mind:

1. Federal Regulations: Under the Gun Control Act of 1968, an 80% lower is not classified as a firearm, meaning it does not require a serial number and is not subject to federal background check requirements. However, once an 80% lower is completed, it transforms into a functioning firearm and is then subject to all applicable laws and regulations, including restrictions on its sale and transfer.
2. State Laws: While federal law does not restrict the sale of 80% lowers, some states, such as California, New Jersey, New York, and Connecticut, have more stringent regulations. These states may require background checks, serialization, or other legal steps before you can legally own or use an 80% lower. It’s essential to verify your state’s specific regulations regarding the purchase, completion, and use of 80% lowers.
3. Transfer and Sale: Once completed, an 80% lower generally transforms into a personal-use firearm. Many states have restrictions on the transfer or sale of personally completed firearms, making it crucial to check state regulations if you intend to transfer or sell a firearm you’ve built.
4. Serialization: Federal law does not require 80% lowers to have a serial number, but certain states mandate serialization once the lower is completed. This requirement aims to keep track of firearms and ensure they are traceable in the event of criminal investigations.

How to Complete an 80% Lower

Completing an 80% lower involves a few technical steps and requires specific tools. Here’s a step-by-step outline of the process:

1. Choose the Right Tools: To complete an 80% lower, you’ll need access to a drill press or milling machine, as well as other tools like drill bits, end mills, and jigs. Some enthusiasts opt for dedicated 80% lower jigs, which make the drilling and milling processes easier and more accurate. Jigs help guide the machining process and ensure you make precise cuts and drills.
2. Set Up the Jig: Attach the 80% lower to the jig, which will hold the lower in place and help guide you in drilling the necessary holes. Proper setup is essential; make sure the jig is properly aligned and secure before beginning the drilling or milling process.
3. Drilling the Trigger Pocket: This is one of the most critical steps. Carefully follow the jig’s instructions and ensure that you are drilling at the proper depth and location. This pocket houses the trigger and fire control group, which are essential to making the lower function as a firearm.
4. Drilling the Pin Holes: The pin holes for the trigger and hammer are also necessary for function. Ensure accurate placement and take your time to prevent mistakes, as improper placement could compromise the functionality of the completed lower.
5. Finish the Lower: After drilling and milling the trigger pocket and pin holes, your 80% lower should be ready for assembly. Follow the manufacturer’s instructions to smooth out rough edges, apply any desired finishes, and prepare the lower for parts installation.
6. Install Components: Now that your 80% lower is complete, you can install the necessary components to make it a functioning firearm. This includes the trigger group, magazine catch, and other components. If you’re building an AR-15-style rifle, the lower will also need to be paired with an upper receiver, barrel, and stock.

Tips for Working with 80% Lowers

1. Use Quality Parts: The quality of components can significantly impact the final build. Invest in high-quality parts from reputable brands to ensure durability and reliability.
2. Practice Safety: Working with a drill press or milling machine requires attention to safety. Wear protective eyewear, gloves, and take your time. Carelessness can lead to injury or damage to the lower.
3. Plan Your Build: Have a clear plan in mind before starting. Consider what type of firearm you want, your intended use, and which components are best suited for that purpose.
4. Understand the Legal Requirements: Ensure you’re fully aware of federal and state laws regarding 80% lowers and the legal implications of building and owning a completed firearm.

Advantages and Disadvantages of 80% Lowers

Pros

1. Privacy: No need for background checks or registration (in most states).
2. Customization: Allows for highly personalized builds.
3. Affordability: Often cheaper than buying a pre-built firearm.
4. Skill-Building: Offers a hands-on approach to learning firearm mechanics.

Cons

1. Legal Complexity: Regulations vary and are complex.
2. Skill Level Required: Not for complete beginners; requires mechanical skill.
3. Risk of Errors: Inaccurate drilling or milling can render the lower unusable.
4. Limited Resale Options: Many states restrict the sale of completed 80% lowers.

Are 80% Lowers Right for You?

For those interested in a hands-on firearm-building experience, 80% lowers provide a unique opportunity. However, they come with responsibilities, particularly in understanding and complying with legal obligations. Novices may find the process challenging, but with patience, the right tools, and proper research, completing an 80% lower can be a rewarding project.

Conclusion

80% lowers offer an appealing combination of affordability, privacy, and customization to gun enthusiasts and hobbyists. While they may require some technical skill and awareness of complex legal considerations, many enjoy the process of building a firearm tailored to their needs and preferences. Before beginning an 80% lower project, take time to understand both the legal and technical aspects to ensure a smooth and successful build.