Navigating the World of 80 Lower Receivers: Your Ultimate DIY Firearm Project

For DIY enthusiasts and gun aficionados alike, 80 lower receivers offer an unparalleled opportunity to create a custom firearm tailored to individual preferences. These products enable buyers to sidestep some of the more traditional pathways for gun acquisition, but they also come with their own unique considerations and challenges. This article aims to provide an in-depth understanding of what 80 lowers are, the pros and cons of using them, and key considerations for your purchase.

Understanding 80 Lower Receivers

An 80 lower receiver is a partially completed receiver for a firearm that is approximately 80% finished. Because they’re not fully completed, these receivers are not classified as firearms under federal law. This means you can purchase and own an 80 percent lower without undergoing a background check. However, once the machining process to complete the receiver is done, it becomes a functional firearm and must be treated as such under the law.

The Appeal of 80% Lowers


One of the most attractive features of an 80 ar lower is the cost. Building a firearm using an 80 lower receiver can often be more budget-friendly compared to buying a factory-assembled weapon.

Skill Development

The hands-on experience of completing an 80 lower receiver is a fantastic way to acquire new skills or hone existing ones. Whether you’re a seasoned machinist or a newcomer, the project is both educational and rewarding.

Unique Customization

The 80 lower receiver provides the ultimate platform for personalization. You can choose specific components, finishes, and accessories to create a truly unique firearm.

The Legal Framework

While an 80% lower is not categorized as a firearm, the completed 80 ar lower is. It’s essential to understand your local, state, and federal laws around firearm ownership and manufacturing to ensure you’re in compliance. Always perform due diligence before embarking on this DIY journey.

What to Consider When Buying an 80 Percent Lower


The choice between aluminum and polymer for your 80 lower receiver is often a matter of personal preference and needs. Aluminum offers greater durability, whereas polymer is easier to machine.


Not all 80% lowers are made equal. Compatibility with other parts and accessories is a critical factor to consider before making a purchase.


The tools you’ll need to complete an 80 lower receiver include a milling machine or a drill press, specific drill bits and end mills, and a vise for stabilization.

Step-by-Step Guide to Completing an 80 Lower Receiver

  • Machining: Use your milling machine or drill press to complete the milling as per the guidelines provided with your 80% lower.
  • Quality Control: After machining, inspect the receiver for any imperfections that could compromise safety or functionality.
  • Assembly: Attach the other components to complete your firearm.
  • Safety Check: Always perform a safety check before attempting to fire your newly assembled weapon.


80 lower receivers have taken the DIY firearm world by storm, offering unprecedented opportunities for customization and skill development. As long as you’re aware of the legal ramifications and skilled (or willing to become skilled) in machining, an 80% lower can be the stepping stone to a truly personalized firearm experience.