One of the biggest trends among AR-15 enthusiasts is to go with an 80% lower receiver for their rifle or carbine.
An 80% lower receiver is an unfinished receiver, which means that it is lower in price (on average) than a complete upper receiver.
Best Budget Pick: Matrix Arms AR-15 80% Lower Receiver
The Matrix Arms AR-15 80% Lower Receiver provides you with a lot of value for the money. All of the exterior machining work is complete, and it only needs the trigger and hammer pockets to be machined to turn it into a fully functioning lower. The 7075-T6 build construction and black anodized finish make it a durable and rust resistant option a well.
Best Polymer Pick: Polymer80 AR-15 80% Polymer Lower Receiver
If you want a polymer lower receiver for your AR-15, don’t look any further than Polymer80 AR-15 80% Polymer Lower. While a bit of extra fitting and drilling will be necessary on your part (particularly for the detent holes), overall this is a very durable lower receiver made out of the same quality materials present on polymer-framed pistols.
Best Overall Pick: Anderson Manufacturing AR-15 80% Lower
If you want an 80% lower receiver that is well built, compatible with most other standard AR-15 components, and easy-to-install, there’s no need to look beyond the Anderson Manufacturing AR-15 80% lower. Just remember to have it finished or coated in Cerakote or Duracoat after you’re done modifying it.
In this guide, we’ll discuss more about what the 80% lower receiver is, how much work you will need to put into it to get it fitted to your rifle, and then the top three best AR-15 lowers for 2020 and their pros and cons.
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What Is An AR-15 80% Lower Receiver?
An 80% lower receiver is simple an AR-15 lower receiver that has been milled or forged, but that lacks afire control group cavity. This means that the user has work to do in order to make it fully functional. This stands in stark contrast to a complete lower receiver, which is ready to go and install right out of the box.
There are also some legal requirements you need to be aware of with your 80% lower receiver as well. Lower receivers are themselves continued to be a firearm, which is why they have a serial number. It’s the lower receiver that houses the fire control group of the AR-15, meaning that without the lower receiver the rifle would be incapable of firing. Furthermore, the lower receiver connects the rest of the rifle together as well.
However, because the 80% lower receiver is unfinished it is not considered to be a firearm by the government. That being said, your 80% lower receiver will most likely come with a serial number on it. If it does not, the ATF recommends that you engrave a serial number on the receiver yourself, but if you don’t this will not be in violation of current Federal law.
Bottom line: complete lower receivers are considered to be firearms, but 80% lower receivers are not. Most of the time 80% lower receivers will come with a serial number on them, but even if they do not this is not a violation of Federal law. The exception to the serial number rule is if you will be finishing the receiver to be sold or transferred lawfully in the future, in which case it must bear a serial number.
In addition, 80% lower receivers do not have to be registered with the government, and an FFL is not required in order to purchase one as well. This means that a person who buy and machines a lower receiver can also legally make an AR-15 rifle.
How To Install An 80% Lower
In case it wasn’t already clear, 80% lower receivers should only be used by those who are willing to put their gunsmithing skills to the test. The good news is that you should attain much personal satisfaction knowing that you built your own rifle.
In general, installing an 80% lower receiver will require you to follow these steps:
- Use a lower vise block to hold the receiver in place
- Locate the magazine release spring, place it into the hole of the receiver, and cover it with the magazine release button
- Press in and flip the receiver over to begin threading
- Find the longer roll pin and trigger guard, and depress down on the pin that is close to the magazine well
- Proceed to slip in the roll pin, and ensure that everything is lined up well
- Gather the bolt catch assembly components
- Place the spring on the plunger, and place it in the hole above the magazine latch
- Attach the spring to the trigger guard, placing the wide side down onto the AR-15 trigger; press down until you see a trigger hole, which is where you’ll put a pin through to hold the assembly onto the receiver
- Place the assembly so the trigger will go through the oval bottom on the receiver; everything should match up perfectly
- Once your trigger pin is through, ease pressure by cocking the hammer down
- Cock the hammer, and insert your safety selector (set it to fire, and then place the safety detent into the hole on the opposite side of the safety indicator)
- Install the rear takedown pin (by placing the detent in the back of the receiver) and then insert the detent spring
- Place the buffer retaining and spring into the hole
- Screw in the buffer tube, and then insert the buffer spring to slide on the stock
These steps will convert your 80% lower receiver into a complete lower receiver. Remember, once your lower receiver is complete, it becomes a true firearm under Federal law.
Buyer’s Guide: What To Look For In An AR-15 80% Lower
These are the most important factors to consider when looking for a new 80% lower AR-15 receiver:
Most lower receivers for AR-15s these days are built out of either polymer or aluminum, with the latter being either 7075-T6 or 6061-T6. 7075 is the higher quality and more durable option, while 6061 is cheaper and more general purpose, but not quite is durable.
The biggest con to aluminum is that being metal, they can be a bit more difficult to drill and mill. Polymer is much softer and will require less effort on your part to drill.
The trade off, however, is that aluminum is more durable than polymer is. This doesn’t mean that polymer is not durable (after all, most striker fired pistols these days are made with polymer frames), but aluminum lowers should be longer lasting.
Your aluminum lower receiver will most likely come with a Type II or Type III hard coat anodized finish, which will make it very rust and corrosion resistant. Alternatively, it may come with a duracoat or cerakote coating, which are both also rust and corrosion resistant and can also give your lower a neat looking depending upon the color that you choose.
Take note, that when you buy an anodized finished aluminum lower receiver, when you drill and mill into the receiver for customization, you will expose the inner layers of the metal that have not been anodized. This means that you would most likely need to get it refinished afterwards. For this reason, consider going with a non-anodized lower receiver first, and then have it finished after.
With polymer, this will not be an issue. Polymer does not come finished and you will only expose the inner layers of the exact same material when you drill and mill into it. However, sometimes polymer will still come with a duracoat or cerakote coating.
Last but not least, it may not impact the function of your rifle, but it still matters to some people and that is the aesthetics of your lower receiver. Take special note of the color, engravings, and design of the receiver. After all, you need to think ahead about how you want your AR-15 to look, and you should want all of the components to match (i.e. the upper receiver and lower receivers should have the same finish and construction materials to maintain consistency).
The 3 Best AR-15 80% Lowers For 2020
Now that we’ve covered what an 80% lower is and what to look for in one, here are the top three best AR-15 80% lowers for 2020:
Anderson Manufacturer AR-15 80% Lower
The Anderson Manufacturer AR-15 80% Lower is an excellent option for a lower receiver. Built from very durable aircraft grade 7075-T6 aluminum, the Anderson is ready for a truly high quality custom build. This lower receiver will need you to drill the trigger group, trigger pin, trigger slot, hammer pin, and the safety selector hole.
The good news is that drilling these holes should be easy, as most users report that they did not run into any substantial issues with the Anderson. This should come as a welcome relief to you, because aluminum is usually more difficult to drill than polymer is.
Another big advantage to the Anderson is that it comes unfinished. As noted previously, when you drill into a lower receiver that is finished, you will expose the unfinished interior layers. By having an unfinished lower receiver, you can then drill the holes without having to worry about anything, and then have it refinished later to your specifications. Admittedly, having your lower finished may be something a truly skilled and experienced gunsmith needs to do, so there will be added costs there.
Anderson has built this 80% Lower to mil-spec standards, so it’s fully compatible with all other AR-15 mil-spec parts that you can find on the market. And as an added bonus, Anderson manufactures this lower right in the United States, so you’re buying a truly American made product.
All in all, the Anderson Manufacturing AR-15 80% lower is a solid choice for an aluminum-made lower receiver. It’s very well machined and easy-to-install, and also compatible with most other lower AR-15 components and accessories available on the market. Just remember to have it finished by a gunsmith after you’re done drilling it, or alternative, you can have it coated in Cerakote or duracoat for excellent rust and corrosion resistance.
- Very well machined
- Very easy to install
- Made in the USA
- Built to mil-spec standards
- Compatible with lots of lower AR-15 parts and accessories
- Since it’s not finished, you don’t have to worry about exposing unfinished inner layers
- Some users have had issues with rear takedown pins
- You’ll need to have it refinished after you’re done drilling
Polymer80 AR-15 80% Polymer Lower Receiver
The Polymer 80 AR-15 80% Polymer Lower Receiver is one of the best 80% lower receivers you can get if you are looking for a polymer made lower receiver. The main advantages of polymer over aluminum are that is lighter in weight and also much easier to machine and drill holes through.
Furthermore, the Polymer 80 is fully compatible with most AR-15 lower receiver parts as well, including many surplus parts that you often find around on the market.
The Polymer 80 ships with the lower receiver itself in addition to a jig kit, which should make customization a relative breeze compared to other lower receivers that do not come with a jig. This, combined with the fact that polymer is already easier to drill through than aluminum, means that the Polymer 80 will be one of the easiest 80% lower receivers to customize.
The Polymer80 AR-15 80% Polymer Lower receiver is an excellent option if you are looking for a polymer made lower receiver. It’s very versatile, easy-to-install, and durable just like a polymer framed pistol. It will require some extra fitting and drilling on your part (particularly for the detent holes) but as a whole this will be a long lasting choice that is also lighter in weight than the aluminum options.
- Easy to install
- Ships with a jig kit
- Great for numerous different applications
- Very versatile
- Not all detent holes are completely drilled
- Some fitting could be necessary, depending on your project
Matrix Arms AR-15 80% Lower Receiver
The Matrix Arms AR-15 80% Lower Receiver is one of the least expensive 80% lower receivers on the market. If you’re looking to put together a custom AR-15 without spending a fortune and furthermore want it to be customized to your needs, the Matrix Arms is worth a close look.
First and foremost, the Matrix is very durable and is designed to handle a great deal of damage, including being thrown at harder surfaces or over cement. This is because of the 7075-T6 aluminum construction, which is one of the most durable options for a lower receiver overall. It’s also compatible with most AR-15 components, including the various inexpensive surplus parts that are floating around on the market.
All of the exterior machining is complete on the Matrix Arms, and the only machining work that you or a gunsmith will need to do is to machine the trigger pocket and the hammer to turn it into a complete upper receiver. The finish is a hard coat anodized black to make it very weather resistant.
Just take note that the Matrix Arms is only compatible with the 5.56 or .223 rounds. If you were looking to build an AR-15 in another caliber, you’re going to be disappointed.
The Matrix Arms AR-15 80% Lower Receiver is a solid choice for the money. Even though it will only be compatible with the 5.56/.223 rounds and no other calibers that the AR-15 is commonly chambered for, it’s still very durable and weather resistant.
- Very weather resistant
- Very durable construction
- Fully compatible with most AR-15 parts and components
- Only compatible with the 5.56x45mm NATO and .223 Remington rounds
And that concludes our list of the top three best AR-15 80% Lowers for 2020. Each of these lowers represents a solid option for your AR-15, but just remember that you will need to most likely put a lot of work into getting it fitted for your rifle or carbine, so be prepared for that.