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Want to build an AR? Keep it simple: Grab a lower assembly.

Not sure what parts you need to go along with your 80% lower receiver?

An AR Lower Assembly is a great purchase for new and first-time AR builders because it comes with all of the parts required for you to create your custom AR-type lower (after fabricating the included 80% lower receiver). Our Lower Assemblies include all the parts necessary to make a functional, complete lower receiver that's ready for an upper receiver assembly.

Lower Assemblies: What's Included

  • Lower Parts Kit
  • 80% Lower
  • Butt Stock
  • Buffer Tube
  • Buffer Spring
  • Recoil Buffer
  • Castle Nut
  • End Plate

Pair With an Upper Assembly

To make your custom AR build even easier, you can pair your lower assembly with one of our quality, barreled upper assemblies. Grab a rifle-length upper for lower kits that come with a buttstock. Grab a pistol-length upper for lower kits that come with no stock, or that come with a pistol brace.

Upper Assembly Install Notes:

  • Do not install a stock on any AR with a barrel less than 16". This is making an SBR.
  • An SBR can only be legally built if you possess an NFA tax stamp provided by the ATF.
  • Lower assembly buffer weights are based on the advertised caliber.
  • .308 lower assemblies include a 3.8-oz buffer.
  • 9mm lower assemblies include an 8.0-oz buffer.
  • Standard lower assemblies include a 3.0-oz buffer.

Want to Build a Custom Upper?

With a complete lower assembly, you cam also buy a stripped upper receiver, and a custom barrel and gas system, bolt carrier group, plus a handguard, and assemble your upper yourself.

Here's how to install your barrel and gas system.

Here's how to install your lower parts kit after fabrication.

80% Lowers: State Laws Vary

Some states have banned 80% lowers and certain firearm parts, or have otherwise restricted the sale and ownership of products we sell. So, be sure to check your local and state laws. We can’t ship our products to certain states. Please check our Shipping & Return Policy before placing an order (See Restrictions).

Your build awaits!


DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At 80-Lower.com, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.

We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, District of Columbia, Hawaii, New Jersey, New York, Rhode Island, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.