Answering a Few FAQs Regarding 80% Lower Receivers 

If you turned to Google with your questions regarding 80% lower receivers, regulations concerning them, or how to complete one, check out some of these FAQs to see if yours is listed – then contact us if you don’t see it or if you have additional questions. 

What is an 80 lower receiver

Officially a “receiver blank” an 80% lower receiver is a lower receiver that has not been machined completely and cannot be used to assemble a functional firearm. You might say that an 80% lower is “80% completed,” but lacks a cavity for the FCG (fire control group); they also cannot accept a trigger, hammer, or safety selector. In addition to being known as 80% lower receivers and receiver blanks, they are also called 80% lowers, 80 lowers, and sometimes as unfinished lowers or even as “home builds.” 

Is an 80% lower receiver a firearm?

The ATF does not consider 80% lower receiver firearms, so they are not regulated or serialized by the federal government. However, many states have laws regulating, restricting or outright banning the purchase, possession or alteration of 80% lower receivers

Are they legal in every state?

No, 80% lowers are not legal in every state, despite the fact that the ATF does not consider them firearms. The following states have either banned them outright or imposed additional restrictions: 

  • New Jersey
  • Rhode Island
  • Connecticut
  • Hawaii 
  • Washington 
  • New York 
  • Washington, D.C.
  • California* (see below, Do I need to serialize an 80% lower receiver?) 

However, this list should not be considered comprehensive and local legislation is in a constant state of flux. Check your local and state laws and consult your own firearms lawyer before attempting to procure or alter an 80% lower receiver

Do I need to buy an 80% lower receiver through an FFL? 

Since the ATF does not recognize 80% lowers as firearms, you do not need to purchase one through an FFL. However, laws in your state may make it illegal to manufacture, purchase, possess or alter an 80% lower. (See above section.)

Do I need to serialize an 80% lower receiver?

The ATF allows non-prohibited individuals to finish receiver blanks, as long as the finished firearm is completed for personal use only. These firearms are not required to be serialized and no paperwork or background checks are required (federally) to do so.

However, some states, such as California, require a user to apply for a serial number and engrave it on the receiver blank before completing the receiver blank. For more information on how to apply for a serial number and engrave it on a receiver blank, please consult our blog on “How to serialize a receiver blank in California.”

What do I need to finish an 80% lower receiver

In order to complete an 80% lower at home, you’ll need an 80% lower and some machining tools: 

  • An 80% lower jig
  • A drill press or a hand drill, as well as compatible bits or mills
  • A vise 
  • Cutting fluid or WD-40
  • A shop vac to clean up swarf 
  • Screwdriver and Allen key sets 
  • Eye and ear protection, as well as gloves to protect your hands.

For a more detailed guide on how to finish an 80% lower with a lower receiver jig, please consult our blog on “How to complete 80% lower receivers.”

What is an 80% lower receiver jig?

An 80% lower receiver jig is sort of like a template that secures your receiver blank and serves as a guide for you to complete the milling. A jig makes it easier to precisely mill out the FCG cavity and the holes for the trigger, hammer, and safety pins. 

Are there 80% lower jigs that can finish more than one type of lower?


Some jigs can complete more than one type of lower receiver blank. For example, our Router Jig Pro (pictured above and accessible via the previous link) can be used to finish AR-15, AR-9, AR-45, AR-10 and .308 lowers. 

What’s the difference between forged and billet 80% lowers?

Forged 80% lowers are also often called Mil-Spec receivers and are formed by drop-forging aluminum (7075-T6 aluminum) into a mold. Billet aluminum lowers are created from extruded aluminum stock (7075-T6 or 6061-T6) that is then CNC machined. 

Should I buy an 80% lower with a special coating? 

That choice is yours, but some lower receivers are anodized or treated with special coatings like Cerakote that improve their corrosion resistance, strength, and dry lubricity. 

Cerakote lower receivers are finished with a very thin layer of polymer ceramic coating. They are waterproof, corrosion-resistant, chemical resistant, and nearly impervious to scratches. Anodized coatings are also water, chemical-corrosion, and scratch-resistant. Both Cerakote and anodized lower receivers have excellent dry lubricity and require less liquid lubricant. 

Don’t see your question here? Call us! 

Do you still have a few questions on 80 percent lower receivers or on what you’ll need to build a firearm? Get in touch with our customer service team for more information. You can contact us at or at 508-834-4223.