Shop AR-15 lower receivers for your next build. The lower is the serialized part of an AR-15, so it is the part that legally counts as the firearm. Pick a stripped lower to choose every part yourself, or a complete lower that is ready for an upper. Every lower ships to your FFL dealer.
Stripped vs Complete vs 80% Lowers
Stripped lower: the bare, serialized receiver. It is the pick for builders who want to choose their own trigger, grip, stock and controls. Finish it with a lower parts kit, then add a buffer tube and stock or brace.
Complete lower: the same serialized receiver with the lower parts kit, grip, buffer system and usually a stock already installed. Pair it with one of our AR-15 upper receivers and you have a working rifle with no lower assembly.
80% lower: an unfinished receiver blank, not a serialized firearm. Federal rules on these changed in 2022, and many states ban or restrict them, so this page lists only finished, serialized lowers that ship to your FFL.
Forged, Billet or Polymer
Forged 7075-T6 aluminum is the mil-spec standard and is what most lowers use. Billet lowers are machined from a solid block for sharper lines and tighter upper fit, at a higher price. Polymer lowers, like FMK’s, cut weight and cost.
Lower, Upper or Whole Rifle?
Not building? Shop complete AR-15 rifles or AR pistols. Building a pistol? Read what is an AR pistol and what is an SBR first. For parts, see our AR-15 trigger guide and AR-15 magazine compatibility guide.
AR Lower Receiver FAQ
Do I need an FFL to buy an AR-15 lower receiver?
Yes. Stripped or complete, the lower receiver is the serialized part and is legally a firearm, even with no parts installed. It ships to your FFL dealer, and you complete a Form 4473 and background check, the same as buying any other gun. A bare lower is usually listed on the paperwork as “other” or “receiver” rather than pistol or rifle, since it can be built as either. Your FFL dealer may charge a transfer fee.
What is the difference between a stripped and complete AR lower?
A stripped lower is the bare serialized receiver with no parts installed, so you choose and install the trigger, safety, magazine release, bolt catch, grip, buffer tube and stock yourself. A complete lower comes with those parts already installed, usually including a stock, and is ready to take an upper. Pick stripped for full control over every part, or complete to skip the lower assembly.
What do I need to finish a stripped lower?
A lower parts kit (trigger, hammer, safety, magazine catch, bolt catch, pins and springs), a pistol grip, and a buffer tube, buffer and spring with either a stock or a pistol brace.
Is an 80% lower the same as a stripped lower?
No. A stripped lower is a finished, serialized receiver sold through an FFL. An 80% lower is an unfinished receiver blank. Under ATF’s 2022 frame-or-receiver rule, upheld by the Supreme Court in 2025, kits that can be readily finished into a working receiver are treated as firearms, and many states ban or restrict them. Check your state law.
Will any AR-15 upper fit any AR-15 lower?
Mil-spec AR-15 uppers and lowers in 5.56/.223 are built to interchange, but fit varies by maker, and some lowers (pistol-caliber or proprietary designs) need a matching upper. Check the product listing before you buy. Need one? Shop our AR-15 upper receivers.
Can I build an AR pistol on any lower?
Only on a lower that has never been built as a rifle. Under federal law, a receiver first built as a rifle stays a rifle, even after the stock comes off, and putting a barrel under 16 inches on it makes it an SBR. The SBR tax has been $0 since January 1, 2026, and since October 9, 2026, ATF no longer requires SBR approval or registration, but many states still prohibit unregistered NFA items. See our SBR guide and check your state law first.
Are forged or billet lower receivers better?
For most builders, a quality forged lower is the right choice. Forged 7075-T6 aluminum is the mil-spec standard, the same process used for military M4 carbines, and it is stronger, lighter and less expensive than billet. Billet lowers are machined from a solid block, which allows more complex shapes and tighter upper fit at a higher cost and weight. In normal use both will outlast the shooter, so billet is worth it for the looks, the tighter fit or features like an integrated trigger guard.
What is the best AR-15 lower receiver for most builders?
The Aero Precision M4E1 is the most recommended stripped lower for most builds. Its threaded bolt catch pin removes one of the most frustrating steps in AR assembly, the integrated trigger guard improves on mil-spec, and the optional tensioning screw on Gen 2 models gives a tight upper-lower lockup. For ambidextrous controls, the ADM UIC offers full ambi function at a more accessible price than the Radian AX556.
Is a lower receiver the same as an AR-15 receiver?
The AR-15 has two receivers. The lower receiver is the serialized part and is legally the firearm; the upper receiver holds the barrel and bolt carrier group. When people search for an “AR-15 receiver” to buy, they usually mean the lower.
Do you sell 9mm and AR-10 lowers?
Yes. 9mm AR builds use dedicated 9mm lowers that take Glock-pattern or Colt-pattern magazines, like the Spike’s 9mm and Battle Arms Development Xiphos lowers. For .308 builds we carry AR-10 lowers like the Aero Precision M5 and Ballistic Advantage BA10. These lowers need a matching upper, so check the product listing before you buy. Stock changes often, so use the In Stock filter.
Can I return a lower receiver?
Returns are accepted within 60 days with a 15% restocking fee. Because a lower is a firearm, it can be returned only before the FFL transfer is completed. Once your dealer transfers it to you, it is no longer returnable.
How Buying a Lower Works
- Order your lower online.
- We ship it to your local FFL dealer.
- At the dealer, fill out ATF Form 4473 and pass the background check.
- Pick up your lower.
Your FFL dealer may charge a transfer fee.
AR-15 Lower Receivers — Stripped, Complete & What to Know
The lower receiver is the only component of an AR-15 that is legally a firearm. It carries the serial number, requires an FFL transfer and background check, and is the foundation to which every other component — trigger group, stock, buffer tube, pistol grip, and magazine well — attaches. Every AR-15 build starts here.
Stripped vs Complete is the primary decision. A stripped lower is the bare serialized receiver with no internal components — the starting point for a custom build where you select and install every trigger, grip, stock, and fire control group yourself. A complete AR lower comes with all internal parts installed — trigger group, safety selector, pistol grip, buffer tube, and typically a stock — ready to accept an upper receiver and shoot immediately. For first-time builders who want to minimize assembly complexity, a complete lower eliminates the need to source and install lower parts kits. For experienced builders who want to specify a match trigger, specific stock, or enhanced fire controls, a stripped lower is the correct starting point.
Material and construction matter but less than marketing suggests. Forged 7075-T6 aluminum is the mil-spec standard — heated aluminum pressed into shape, producing the densest grain structure and highest strength-to-weight ratio. This is what military M4 carbines use and what the vast majority of quality AR lowers are made from. Billet lowers are machined from a solid block of aluminum, allowing more complex shapes and tighter tolerances but at higher cost and weight. Both will outlast the shooter who builds on them in normal use. A $50 PSA forged lower performs identically to a $300 billet lower from a premium manufacturer in every measurable function test — the premium pays for tighter upper/lower fit, ambidextrous controls, and machining aesthetics.
The Aero Precision M4E1 is the most popular stripped lower in current build data — its threaded bolt catch pin, integrated trigger guard, and optional tensioning screw for tight upper fit make it the practical choice for most builders. PSA's complete lower assembly is the most-added complete lower in build data, driven by its combination of price and ready-to-shoot convenience.
For trigger selection to install in your lower, see our AR-15 trigger guide. All lower receivers transfer through a licensed FFL dealer — they are legally firearms regardless of whether they are stripped or complete.
Building out your lower? See our AR-15 trigger guide and AR-15 magazine compatibility guide. Building a pistol? Read what is an AR pistol and what is an SBR before you choose a lower. Browse all of our firearms & ammo buying guides.