The Ultimate Guide to 80% Lowers: Crafting Your Own Firearm

For gun enthusiasts, there’s no greater sense of accomplishment than building a firearm from scratch. While most firearms are purchased as complete units, the rise of 80% lowers has made it easier than ever for individuals to build their own guns. Whether you’re into AR-15s, AR-10s, or other platforms, 80% lowers provide a unique opportunity to customize and craft your weapon the way you want it. In this guide, we’ll cover everything you need to know about 80% lowers, from their legal status to how to complete them yourself.

What Exactly is an 80% Lower Receiver?

An 80% lower is a partially finished lower receiver. These parts are considered “unfinished” because they have not yet been fully machined to the point where they can function as a firearm. They are typically made from high-quality materials like aluminum or polymer, and their purpose is to serve as the foundation for a custom firearm build.

Legally speaking, 80% lowers are not classified as firearms under federal law. This distinction allows individuals to purchase these parts without the need for a background check, making them an appealing option for those who want to build a firearm privately.

The Appeal of Building with 80% Lowers

There are several reasons why firearm enthusiasts gravitate toward using 80% lowers for their builds:

1. Customization: One of the most attractive features of using an 80% lower is the level of control it gives you over your firearm’s specifications. From selecting the barrel and trigger mechanism to choosing grips and finishes, you can customize your firearm to meet your exact preferences.

2. Cost-Effectiveness: Building a firearm from scratch can often be more affordable than purchasing a fully assembled weapon, especially if you’re able to source parts directly and avoid dealer markup. 80% lowers allow you to skip the cost of buying a complete receiver and invest more money into the components that matter most to you.

3. Educational Experience: Completing an 80% lower isn’t just about saving money or customizing your firearm; it’s also a fantastic learning opportunity. If you’re new to gunsmithing or machining, building from an 80% lower is a great way to develop your skills and understand the intricacies of firearms.

4. Privacy: Many people appreciate the privacy that comes with building their own firearm. Because 80% lowers are not legally considered firearms, purchasing them doesn’t require a background check or registration. Once completed, the firearm will need to be treated as a legally registered weapon, but the initial process offers a degree of anonymity.

Legal Considerations When Working with 80% Lowers

While the federal government allows the purchase of 80% lowers, it’s crucial to understand that different states have different regulations regarding their use and completion:

• Federal Law: According to federal law, 80% lowers are not firearms, meaning that they can be bought without a background check or FFL. However, once you complete the lower, it becomes a firearm and must be treated as such, with all applicable laws in place.
• State Laws: Some states have stricter regulations around 80% lowers. For instance, in states like California, New York, and New Jersey, you may be required to add a serial number or register your finished firearm. Be sure to check your state’s laws before you begin your build to ensure full compliance.
• Completion Makes It a Firearm: Once you complete your 80% lower by finishing the machining process, it becomes a legal firearm under both state and federal laws. This is when you need to ensure you are abiding by all legal requirements, including adding a serial number if necessary, and following laws regarding firearm ownership.
• Selling and Transferring: If you plan to sell or transfer your completed firearm, you must follow the applicable regulations. Many states require a background check for firearm transfers, and federal law mandates that any firearm sold or transferred across state lines must go through an FFL dealer.

How to Complete an 80% Lower: The Process

Completing an 80% lower requires both the right tools and knowledge. Here’s a breakdown of the process:

1. Gather the Necessary Tools: Depending on how detailed you want to get with your build, you can use basic tools like a drill press and hand tools, or opt for more advanced tools like a CNC machine for precision. You’ll also need a jig kit to guide your drilling and milling operations.

2. Select a Jig Kit: A jig is an essential tool that ensures your cuts and drills are done correctly and with precision. Jig kits come with everything you need to complete your 80% lower, including the templates and instructions. Many kits are designed to be used with a drill press, though some are compatible with CNC machines for faster and more accurate work.

3. Machining the Fire Control Pocket: The most important step in completing an 80% lower is machining the fire control pocket, which houses the trigger mechanism. This part requires careful attention, as it’s critical for the proper functioning of your firearm.

4. Drilling and Cutting: Once the fire control pocket is machined, you’ll need to drill holes for the trigger pins and the takedown pin. These steps require accuracy to ensure that the parts fit together properly. You may also need to make additional cuts for things like the magazine well or buffer tube.

5. Assembly: Once your 80% lower is fully machined, it’s time to assemble the rest of your firearm. Attach the upper receiver, stock, buffer tube, trigger mechanism, and other components. Make sure to test everything thoroughly before firing.

Testing and Ensuring Safety

After completing your firearm, it’s essential to ensure its safety and functionality:

• Function Check: Run a function test to ensure that all components, such as the trigger, safety selector, and magazine release, work properly. Pay attention to any irregularities that might indicate an issue with the build.
• Professional Inspection: If you’re new to gunsmithing or want an expert’s opinion, consider taking your completed firearm to a professional gunsmith for inspection. They can verify that your build is safe to use and meets all necessary standards.
• Safe Firing: Always test your completed firearm in a safe and controlled environment, such as a shooting range. Wear the appropriate safety gear, including ear protection and safety glasses.

The Pros and Cons of 80% Lowers

Before deciding whether to work with an 80% lower, it’s important to consider the pros and cons:

Pros:

• Affordable option for building a firearm.
• Complete control over customization.
• Educational experience in gunsmithing and firearms assembly.
• No background checks or registration required for purchasing the lower.

Cons:

• Requires time, tools, and effort to complete the lower.
• Potential legal complexities depending on state regulations.
• May require access to specialized equipment for precise machining.

Conclusion: Is an 80% Lower Right for You?

Building a firearm from an 80% lower receiver is a rewarding process that offers the chance to create a custom weapon while developing valuable skills. It’s a great option for those who want to save money, learn more about firearms, and enjoy the satisfaction of crafting something unique. However, it’s important to be prepared for the time commitment, the tools needed, and the legal responsibilities involved.

To get started on your own build, visit 80-Lower.com for a variety of 80% lowers and related products that will help bring your firearm project to life.