Buying a Firearm

Do You Need an FFL to Buy a Lower Receiver?

Short answer: yes. If you are buying a standard serialized lower receiver, it is legally a firearm, which means it has to ship to a licensed dealer and you complete a background check before you take it home, exactly like buying a complete rifle or pistol. This surprises a lot of first-time builders, who reasonably assume that a bare aluminum part is just a component. Federally, it is not. The receiver is the gun. Here is why that is, how the purchase works, and the one area where the rules get more complicated.

Why the receiver is the “firearm”

A modern rifle or pistol is made of many parts, but federal law designates one of them as the firearm itself: the part that houses the fire-control components and carries the serial number. On an AR-15, that is the lower receiver. On most other guns it is a comparable serialized frame or receiver. Everything else, the barrel, the upper, the stock, the handguard, the trigger group sold as parts, is just a component you can generally buy without a background check.

Because the serialized receiver is legally the firearm, it gets treated like one at every step. It carries the serial number, it is what the manufacturer logs and the dealer records, and it is what the 4473 and background check attach to. The fact that it cannot fire a shot on its own does not change its legal status. The law follows the serialized part, not the finished gun.

How buying a lower receiver works

In practice, buying a stripped or complete lower receiver works just like buying any firearm online or across the counter. If you order one online, it does not ship to your house. It ships to a licensed dealer near you, who receives it, logs it, and handles the transfer. You go in, fill out the 4473, pass the background check, and take it home. The full step-by-step is the same as any transfer, covered in the article on how FFL transfers work.

A few practical points follow from this:

  • You can only buy one part with a background check, and it is the receiver. The upper, barrel, and other components can ship straight to your door.
  • The receiver still counts as a handgun or long gun for purchase rules. Depending on the configuration it is intended for and your state’s rules, age and residency requirements can apply, so confirm before you order.
  • A local shop can receive and transfer a receiver the same way it handles any firearm shipment. Calling ahead so they expect it is a good idea.

Stripped vs complete lowers

You will see lowers sold two ways. A stripped lower is just the bare serialized receiver with none of the internal parts installed. A complete lower comes with the fire-control group, grip, and stock already assembled. Both are legally firearms and both transfer through an FFL the same way. The only difference is how much assembly is left for you to do, not the legal process to acquire them.

For a first build, a complete lower removes the fiddly trigger and detent installation, while a stripped lower costs less and lets you choose your own trigger. Either way, the background check is identical.

The tricky part: unfinished or “80 percent” receivers

This is where it gets complicated, and where you should be careful. For years, unfinished receivers, often called “80 percent” lowers because they are not fully machined, were sold as raw material rather than firearms, which meant no serial number and no background check. That landscape has changed. Federal rules around unfinished receivers and parts kits that can readily be made into a working firearm have tightened, and the definitions have been the subject of regulation and ongoing litigation.

Because this is an active, shifting area of law, it would be a mistake to treat any general statement as current. The safe approach is simple: do not assume an unfinished receiver is exempt from background-check requirements, and verify the current federal rules and your state’s rules before buying one. Several states regulate these items more strictly than federal law does, and some require serialization or ban certain kits outright. When in doubt, ask a licensed dealer or check the current ATF guidance.

State rules matter a lot here

Even for ordinary serialized receivers, state law adds another layer. Some states regulate the configuration a receiver can legally be built into, particularly for AR and AK-pattern rifles, and a build that is standard in one state may be restricted in another. Massachusetts and several other states have specific rules on semi-automatic rifle features and on what can be assembled, so a receiver that is simple to buy and build elsewhere may carry real restrictions there.

This is the same point that runs through any firearm purchase: the federal process is only half the picture, and your state’s rules decide the rest. If you are planning a build, sort out the legal configuration for your state first, then buy the parts. The guides on AR-15 vs AR-10 and choosing your first rifle cover how to think about the platform itself.

Firearm and receiver laws vary by state and town and are an active area of federal regulation, especially for unfinished or self-assembled receivers. Confirm the current federal rules and the rules that apply where you live before you buy or build. This article is general information, not legal advice.

Frequently asked questions

Is a stripped lower receiver really a firearm? Yes. Federally, the serialized receiver is the firearm, even with no other parts installed. It ships to a licensed dealer and requires a background check to transfer, just like a complete gun.

Can a lower receiver be shipped to my house? No. As the legally controlled firearm, a serialized receiver has to ship to a licensed dealer near you for the transfer. The other parts of a build, like the upper and barrel, can ship to you directly.

Do I need a background check for the upper, barrel, or parts kit? Generally no. Those are components, not the firearm, so they are not subject to the same transfer process. The serialized receiver is the part that requires the check.

What about 80 percent or unfinished receivers? The rules here have tightened and remain in flux. Do not assume they are exempt from background-check requirements. Verify current federal and state law before buying one, and ask a licensed dealer if you are unsure.