80% Lowers are the latest trend among AR-15 enthusiasts. This unfinished receiver is low on price and helps the user avoid some legal formalities while enjoying the fact that he’s machining the receiver himself.
Here we’ll be talking about what an 80% lower receiver is, how much work and effort is required to customize it and the legal requirements associated with. We will also discuss some factors important to consider before buying. To help you out with this task, this article also outlines some of the best options currently available in the market.
Comparison Chart of the Best 80% Lower Receivers
James Madison Tactical AR-15 80% Polymer Gen 2
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Polymer80 AR-15 80% Polymer Lower Receiver and Jig Kit
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Anderson Manufacturing AR-15 80% Lower Receiver
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Brownells AR-15 80% Lower Receiver
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Matrix Arms AR-15 80% Lower Receiver Forged
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What is an 80% Lower Receiver?
An 80% lower receiver is nothing but a simple milled or forged piece of metal which looks like an AR-15 lower receiver but without the fire control group cavity. In simpler terms, it is an unfinished AR-15 lower receiver which requires the user to do some milling and drilling in order to make it functional.
The part where the trigger assembly is installed is plain solid, and the user must drill and machine this part to convert it into a stripped lower receiver.
Legally, a lower receiver is considered to be a firearm itself and hence required to bear a serial number. That is because a lower receiver houses the fire control group and connects all the basic functioning parts of a rifle.
Due to its unfinished design, this is not considered a firearm by the ATF. This means that it does not require a serial number for sale and purchase. A rifle made with such a receiver can be owned and used in the state, county or city you reside in without any serial number, at least under federal law.
On the other hand, the ATF does recommend user of such self-made AR-15 rifles to engrave some serial number and info on such receivers. This helps in case such firearms are lost or stolen. (We’ll try to stay apolitical for the purposes of our article here).
It is important to note here that an 80% lower receiver is not considered a firearm only if used for personal use. If you finish this receiver for a weapon to be sold or lawfully transferred in the future, it must bear a serial number in accordance with 27 CFR 478.92 regulations. You should also always check with your local firearm laws and regulations beforehand.
How Much Work Is Involved?
Frankly speaking, 80% lowers are specifically for serious DIYers. If you love machining and are ready to put in some skills and effort, you ought to invest in one so you can have real satisfaction knowing the extent you went to in building your rifle..
Converting this piece of metal into the receiver you want can be done using a variety of different methods and tools. There are a ton of videos out there on the internet to help you out with this.
You can finish this project easily and economically if you have a manual end mill or a drill press. If you have a precision jig, this process will get easier. You can find a good precision jig online at many stores.
If you are working with aluminum lowers, the process will be a bit time-consuming and difficult compared to working with polymers. The reason is obviously the difference in the hardness of these materials.
The time and effort to complete a task like this depends upon the tools you use (manual or automatic) and your skills.
Legal Requirements for Registration
Legally, an 80% lower receiver does not have to be registered or have a serial number. They can be sold to anyone with or without an FFL. A person who buys an one can machine and drill it to make a complete lower receiver and hence a complete AR-15 rifle.
Such weapons do not require to have a serial number under federal law. Be sure to be aware of your own state’s laws (looking at you, Californians!).
However, the user can neither transfer nor sell this firearm. If the user intends to sell or transfer such an AR-15 he/she has to get their weapon registered and serialized.
The laws about sale and transfer are somewhat confusing. That’s because you can gift such a weapon to someone if you manufactured it for your own use. On the contrary, if you manufactured such a weapon with the intent of gifting it, you must be sure it’s serialized.
The catch here is how is somebody (from the law) going to prove your intention. Confusing, isn’t it?
None of this is legal advice; we’re only presenting our own understanding of the law. Local laws can vary as well.
Factors to Look For
There are several factors you must consider seriously before choosing an 80% lower receiver for customization. These include:
The first and foremost factor to consider when choosing an 80 lower is the material. Lower receivers are generally made either of aluminum or polymer.
Aluminum can be further divided into 6061-T6 and 7075-T6 variants, where the former is more like a general-purpose material and the latter is of high quality and more durable.
Aluminum lowers, being pure metal, are a bit difficult to mill and drill. Polymers on the other hand are softer and require less effort for customization.
But on the contrary, aluminum is long-lasting and more durable than polymer. We recommend using aluminum lowers but it is still a matter of personal discretion.
80% lowers are generally type II or type III hardcoat anodized which makes them abrasion- and corrosion-resistant. Several lowers bear different kinds of finish such as cerakote and duracoat.
Buying an anodized 80% lower might not be an intelligent choice. That’s because you’ll be milling and drilling the receiver to customize it, which is eventually going to expose the inner layers of the metal which are not anodized.
This means you’ll have to get the lower receiver anodized after finishing it. So it’s better to stay with the non-anodized or simple aluminum 80% lowers.
On the other hand, polymer receivers don’t face such an issue because you are only exposing layers of the same material while machining.
Always aim to buy an 80% lower receiver from a well-known manufacturer or a trusted firearms dealer.
80% lowers are required to be drilled and machined for completion, so they must have tight tolerances and precise working points.
Low-grade manufacturers can deliver hit-or-miss products which can eventually lead you into trouble while finishing.
You want your weapon to look good, right? Aesthetics are also an important aspect while choosing an unfinished lower for customization.
Consider the color, design and any engravings on the 80% lower that matches your aesthetic needs.
Quick Take – The Best AR-15 80% Lowers
These are our recommendations for the best AR-15 80% lowers:
- James Madison Tactical AR-15 80% Polymer Gen 2 Lower Receiver
- Polymer80 AR-15 80% Polymer Lower Receiver and Jig Kit
- Anderson Manufacturing AR-15 80% Lower Receiver
Best AR-15 80% Lower Receivers
Let’s look at a few of the top models that meet our criteria for a quality piece you can build your own rifle around.
Manufactured from high-grade polymer, this Gen 2 80% lower receiver from James Madison Tactical is easy to customize and install. This receiver is fairly priced as a polymer lower.
Machined to perfectly fit all AR-15 parts, the receiver features pre-machined areas such as buffer tube threads, the bolt release cavity and the rear pivot pin. The receiver includes a trigger guard as well.
Compared to other polymer lowers, this one is extremely durable and in some cases comparable with an aluminum receiver. This is a multi-cal lower receiver fit for most uppers of the AR-15 platform.
Just be sure to customize it properly as the manufacturer doesn’t accept returns after any changes to the product!
Polymer80 offers this polymer 80% lower receiver offers the best value for the money. The package includes an unfinished lower receiver along with a jig kit which makes customization a breeze.
The jig kit also includes the necessary end mill bits and other components so you don’t have to gather tools and resources.
Available in black, flat dark earth, and gray colors, this model offers multiple options to help you with the aesthetics of your rifle. It’s compatible with .223 REM and 5.56 NATO ammunition.
Anderson Manufacturing creates this unfinished lower receiver machined from forged 7075-T6 aluminum for improved durability and performance. The receiver is incredibly low on price respective to its quality.
Operations left to be completed include the fire control group milling, trigger and hammer pins, and the safety selector hole. The receiver is multi-cal when finished and offers extensive customization options to the user.
This receiver has been designed to mil-spec standards and is made in the USA, so you can be sure of the quality. A jig is not included in the package so you’ll have to buy or arrange for it separately.
Some users have complaints with the Anderson Jig so you might consider looking elsewhere.
This receiver is perfect to create a rifle for tactical uses and target practice.
This is a good 80% lower receiver branded for the renowned dealer Brownells. This lower has been machined from 7075-T6 forged aluminum and comes equipped with a takedown lug pocket.
The broached magazine well helps in changing mags conveniently upon completion of this receiver. The receiver is compatible with a wide range of jigs so you don’t need to buy a new jig if you already have one.
The receiver is multi-cal and will fit any standard AR-15 Upper Receiver. It is available in hardcoat anodized and non-anodized variants so you may choose the one you like.
This version made from billet aluminum is fairly priced and bears the trust of a renowned brand.
This 80% lower receiver has been machined from 7075-T6 forged aluminum and gives the user a chance to machine out the interior pocket themselves.
All the exterior machining has already been done and the user only needs to machine the hammer and trigger pocket for completion.
This receiver supports 5.56 NATO cartridge and is compatible with all standard AR-15 uppers. It’s available in hard coat anodized black and non-anodized variants.
The receiver is black in color and looks aesthetically pleasing. It also features a takedown lug pocket which allows the user to take on an advanced AR build.
6. Kyntec Corporation – AR-308 Shorty (2.5″) Collapsible Stock Recoil Buffer
The Kyntec Corporation AR-308 Shorty Collapsible Stock Recoil Buffer will help you achieve greatly reduced recoil, which just about any gun owner can appreciate. Designed with a variety of applications in mind, including law enforcement, competitive shooting, and sportsman shooting, this buffer not only provides exceptional recoil reduction but also helps to prevent excessive wear and tear on your AR. Not only built for high-end applications, but tested for them as well, the U.S. Army uses the Kyntec Corporation AR-308 Shorty and has proven them to be far superior both in field tests and in active combat.
You can expect a solid reduction in cyclic rates, which not only will improve your accuracy, but also help save ammunition as a result. Made of quality materials, the sealed hydraulic cylinder is 17-4 stainless steel with a nickel-plated cylinder rod, topped off with a high-impact striker cap. These materials not only improve performance but ensure the buffer lasts a very long time.
As it’s easy to replace a standard mass and spring buffer, this upgrade is a no-brainer for serious gun owners looking to improve performance and efficiency by using the same high-quality product as the U.S. Military.
Very Easy to Install Even for Beginners
U.S. Army-Tested and Approved, and Used in Combat
Demonstrated to Greatly Reduce Cyclic Rates, Improve Recoil, and Save Ammunition
Made of High-Quality Parts for a Long-Lasting Solution
Helps Prevent Wear and Tear on Your Weapon
A Bit Pricey, But it Will Pay for Itself Over Time in Reduced Wear and Saved Ammunition
While replacing your stock with this Kyntec Corporation buffer is a bit of an investment, it’s well worth the advantages of improved recoil, reduced wear and tear, and lowered ammunition burn, especially since it’s one of the easiest upgrades anyone can make.
How to Install an 80% Lower:
Installing an 80% lower on your AR-15 is affordable and fun, but requires a good bit of work, so carefully follow the steps below and reference our video for assistance:
Start with the magazine catch. Use a lower vise block to hold it in place. Locate your magazine release spring, place it into the hole, and cover it with the magazine release button, serrated side up. Press in and flip your receiver over and start threading. Be sure the catch won’t scrape against the receiver.
Move on to the trigger guard assembly. Find the longer roll pin and trigger guard, and depress the pin closest to the magazine well. Now, slip it in, ensuring everything is lined up, and use either a hammer or your fingers.
Gather your bolt catch assembly parts and place the spring on the plunger and drop it in the hole above your magazine latch. Depress the catch, using a hammer if need be.
Moving back to the trigger guard, attach the springs. Place the wide side down onto the trigger so the spring stays in position while you place the disconnector on the spring. Press down, and you’ll see the trigger hole. You’ll place this assembly onto the receiver and put a pin through this hole.
Place your assembly so the trigger will go through the receiver’s oval bottom. Match everything up so you can see the pinhole.
Check the hammer and spring placement. Once the trigger pin is halfway through, cock the hammer down to ease the pressure. A brass punch may make this step easier.
Important: Do not dry fire! You’ll damage the lower receiver if you do.
Cock the hammer and insert the safety selector. Set position to “fire,” and place the safety detent into the hole opposite the safety indicator. Place the safety detent spring in the hole of the grip. Match the spring to the safety selector hole, ensuring it is still in “fire” position, and screw in the grip.
Install your rear takedown pin, placing the detent in back of your receiver, and insert the detent spring.
Place the buffer retainer and spring into the hole and screw in the castle nut.
Put the end plate into the correct orientation and screw in the buffer tube, stopping before the tube reaches the retainer.
Match the end plate with the receiver, screw in the last castle nut, and place the detent spring in first, followed by the detent, and lastly by the pivot pin.
Insert the buffer spring and slide on the stock. Pull your adjustment tab and move the stock inwards. You’re done!
An 80% lower receiver lacks the fire control group cavity which has to be drilled and machined in order to make it operational. They allow users to customize their AR-15 the way they want. Factors such as material, finish, brand and aesthetics should be considered before buying.