What Are 80 Lower Receivers?

People building the AR-15 recognize that they have to start with the stripped lower receiver of the rifle. The stripped lower receiver is the rifle’s regulated and legal component, and the rest aren’t. The Bureau of Alcohol, Tobacco, and Firearms do not serialize, regulate, or control the other parts.

What Are 80 Lower Receivers?

The lower component of the firearm is already a firearm itself, but it’s nothing more than a gun housing that holds the other parts, namely the magazine, hammer, trigger, disconnector, and safety.

The lower receiver is attached to the upper receiver that holds the firearm’s barrel, bolt, and the buffer. Thus, the stripped lower is a firearm legally.

But, what about the 80% lower receiver?

This is the stripped lower receiver’s unfinished version, hence not a weapon itself.

The reason is that it wouldn’t be functional at all even if you have the gun components you need for the rifle.

The 80% lower is unfinished; thus, it won’t accept every required component of the rifle.

So, what parts of the 80 percent lower should you complete so that you can make it functional?

NOTE: You need to do drilling and fabrication!

You need to drill the trigger pinhole, hammer pinhole, and safety selector lever hole. In addition, you have to fabricate the fire control group cavity.

Meanwhile, some of its sections have already been done, and they are the pistol grip hole, bolt catch, magazine release, magazine well, trigger guard pinholes, and buffer detent hole.

Others are the buffer tube threads and housing, front and rear take down holes, and upper receiver rear lug pocket.

Drilling the pin holes and completing what needs work in your 80% lower receiver will prepare it for assembly. There are sellers of the buffer tube kit and lower parts kits that you can purchase to get started.

What are the types of 80% lowers?

Most of them, which are the unfinished version of the stripped lower receiver, are designed and made for the AR15.

Such lowers can work with other calibers like the 6.5 Grendel and 300 Blackout and with 5.56 and .223 magazines and uppers.

You’ll also find .308 lowers for the rifle platform AR-10 / LR-308 that can also work to chamber 6.5 Creedmoor.

Meanwhile, there are also frames for some handguns like the Sig P320, GLOCK, and 1911.

Are 80% Lowers Legal?

Not all states permit the use of 80% lowers, and some states even banned them. California, for instance, requires a user to serialize a frame blank/frame receiver before machining it as well as to complete a background before assembling a gun.

On the other hand, some states altogether prohibited the use, fabrication, sale, and ownership of these receiver blanks.

Stripped Lower vs. 80 Lower Differences

The 80 lower is the unfinished version of the stripped lower.

It’s only been partially milled, so it needs more work on your end before you can make it functional.

You don’t also need to have a background check to have it because it’s not considered a firearm.

Meanwhile, the stripped lower is the lower receiver itself that doesn’t include the magazine, safety, and trigger.

Possessing this, you’ll need a background check and an FLL. This lower allows for customization, including on the trigger and grip.

Things You’ll Need for the 80% Lower Receiver’s Milling Process

Most shooters can accomplish milling and drilling the receiver’s interior at home in a relatively simple manner.

They can also find manufacturers selling the milling jigs that are what hold the receiver as well as guide both the router and milling tool kit consisting of drill bits and end mills.

At the very least, you’ll need a jig kit and a tool kit to finish milling your 80% lower.

Benefits of an 80% lower

What’s the point of buying an 80% lower when you could just buy a finished lower?

For one, you don’t need to buy it from a licensed dealer because by definition an 80% lower is not a firearm.

Thus, manufacturers also don’t need to put a serial number on it.

To buy it, you don’t also need to accomplish form 4473 or submit a background before you could.

80% lowers are legal. Shooters also retain ownership, while also legally owning one that’s not registered or recorded.

NOTE: Even if it’s legal to use a lower to mill your firearm and then sell it when you want to, you must apply a serial number to the receiver before a sale aside from complying with all the applicable laws surrounding and covering gun sales.

And while the upfront cost of spending on equipment would be high and sometimes prohibitive for some shooters, not mentioning the labor that comes with assembling a firearm, investing on these tools and spreading the cost over several receivers for assembly can lower this cost.

Building several ghost AR-15s, which would be off the grid, gives shooters the ability of owning at least one firearm.

A 80% lower receiver manufacturer can also offer shooters with a wide range of choices on the type of receivers, including billet or forged as well as both raw or anodized receivers based on one’s personal preference.


Should you put a serial number?

You don’t need to put a serial number for making a gun for personal use. However, gun laws can be different from one state to another. It would be wise to check gun laws and rules in your location to be on the safe side.

Why 80% lowers silver?

It is because most of them are sold in raw aluminum, although there are sellers that sell them with anodized coating.

Is it hard to complete an 80% lower?

Yes, it can be. In fact, you need some tools and equipment to complete it. Some of these include a power drill, drill press, and a wood router. You might also have to have some special mechanical skills and interest to finish it. But with some patience and practice, it is doable.

80 percent lowers may also cost as much as a drilled and milled stripped lower, because again, you need to have special tools to complete it. That’s why some shooters also find milling the unfinished lower time consuming, too.

Do I need to fill out form 4473 or visit FFL before buying an 80% lower?

No, you don’t need to, because these receiver blanks or 80% lowers are not restricted to FFLs, and filling out form 4473 isn’t required either because it has no serial number.

What else is needed to assemble a receiver blank?

Take note that these 80 lowers are sold separately from other components that you need to machine or fabricate a gun. You’ll also need upper parts aside from the buffer system and lower parts kit.

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