Best 9mm AR Lowers for Your AR-9 Build

Pistol caliber carbines are more popular than ever.

At the same time, more and more gun owners are custom-building their own ARs, upgrading what they own, or converting from one cartridge to another.

The result? A growing market for 9mm lower receivers.

Choosing a 9mm lower can be tricky. Even if you know your stuff, the sheer number of options can seem daunting.

Fortunately, you’ve got us and we love to help. Let’s get started!

THE QUICK LIST

1. Best Overall

   Angstadt Arms 0940 Lower Receiver

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2. Best Budget

   PSA PX-9 Lower Receiver

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3. Best Customization

   Aero Precision EPC-9

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4. Best Upper and Lower

   Rainier Arms 9mm Billet Receiver Set

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5. Best Unfinished Lower

   80% Arms AR-9 80% Lower Receiver

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How We Tested the Best 9mm AR Lower Receivers

We’ve shot thousands of rounds and spent hundreds of hours with various 9mm AR lowers between our hands-on reviews, shooting events, and our own personal collections.

The models listed below are some of our favorites that we’ve had hands-on time with. When possible, we link to the respective review for each model. All hands-on  reviews at Pew Pew Tactical adhere to a strict testing protocol. That includes 500 rounds through every review model.

All 9mm AR lowers are prioritized by ease of assembly, reliability, and value. If you’re going to spend money on a lower we recommend, it better mate up with an upper easily and go bang every time!

How to Choose the Best 9mm AR Lower Receiver

The AR platform works kind of like Legos — you can build whatever you want!

Well, almost anything. While there’s a huge amount of commonality across manufacturers, there are some components that aren’t universal. An AR-15 doesn’t share all its parts with an AR-10, for example.

In the world of 9mm ARs, there are some instances where one manufacturer’s lower receiver will only work with an upper from the same brand. Before you start ordering parts, make sure you have a complete parts list and verify that everything you picked will play nicely together.

While you’re at it, think about how much work you’re willing to take on yourself. Do you want to slap fully assembled upper and lower receivers together and call it a day? Would you rather pick each individual component? Does drilling out a blank sound like a fun project?

It’s always a good idea to have a vision of your finished project before you start throwing money around.

Best 9mm AR Lower Receivers

1. Angstadt Arms 0940 AR-15 Lower Receiver – Best Overall

Pros

• High quality
• Compatible with 9mm, .40 S&W, and .357 Sig
• Last-round bolt hold-open

Cons

• Somewhat expensive

The Angstadt Arms 0940 AR-15 Lower Receiver is a great option for people who want a stripped lower.

As the name implies, it works with Glock magazines. We love its flared magwell because it makes it makes reloading a little bit quicker.

This lower is compatible with 9mm, .40 S&W, and .357 Sig, so you could also use this receiver for other PCC builds as long as you stick to Glock-pattern 9mm double-stack mags.

More bang for the buck? Sign me up!

Like the rest of these lowers, it uses 7075-T6 aluminum and a matte black hard coat anodized finish. Weighing 10 ounces, this one is pretty light relative to other lowers.

Rounding out the features are a last-round bolt hold-open, an oversized trigger guard, and a threaded bolt catch screw.

It works with any mil-spec upper, a 9mm bolt carrier assembly, and a standard AR-15 hammer.

Check out our complete UDP-9 review for all the details!

2. PSA PX-9 Forged Complete Glock-Style Lowers – Best Budget

Pros

• Fully assembled lower receiver
• Uses Glock magazines
• Great bang for the buck

Cons

• No last-round bolt hold-open

If you already own a stack of 9mm Glock magazines, PSA has a complete lower receiver just for you. It’s our favorite entry-level 9mm AR lower receiver.

This lower is designed to pair with most 9mm uppers at PSA.

Unfortunately, it doesn’t feature last round bolt hold open capability so a dry mag won’t automatically lock the bolt open.

You’ll probably find your AR is empty when you hear a click, then have to drop the mag, insert a new mag, and rack the bolt.

That can be annoying, but it keeps costs down, so you can buy this lower on a budget.

Want more info? Read our hands-on review of the PSA PX-9!

What’s your take on the PX-9?

3. Aero Precision EPC-9 Lower Receiver – Best Customization

Pros

• High-end components
• Available as a stripped or assembled lower receiver
• Compatible with 9mm and .40 S&W

Cons

• Expensive

Aero Precision is famous for its high-quality AR parts, and the EPC-9 platform is no exception.

It’s a multi-caliber lower that can run 9mm and .40 S&W from standard Glock magazines via the flared magazine well.

To make installation easier, this lower uses a standard AR-15 pin lug pattern and has a threaded bolt catch pin and threaded takedown pin detent recess. 

It’s machined from 7075-T6 aluminum and has an enlarged trigger guard. 

Weighing 12.8 ounces, the Aero Precision EPC-9 lower receiver is pretty lightweight. 

The lower receiver comes in anodized black and FDE Cerakote finishes, so you can pick the color that best fits the overall vibes of your AR-9 build.

In addition to the stripped receiver, you also have the option to buy a variety of complete lower configurations with different stocks and pistol grips.

Make sure to check out John’s full review on the Aero Precision EPC-9 Build here or watch the video review below.

4. Foxtrot Mike Products FM-9 Billet Lower Receiver – Best Fully Assembled

Pros

• Fully assembled lower receiver
• Compatible with most off-the-shelf parts
• Last-round bolt hold-open

Cons

• A2-style pistol grip

Next up is the Foxtrot Mike Products FM-9 Billet Lower Receiver.

The receiver itself is compatible with mil-spec AR-15 components and Glock-style magazines.

When those magazines run dry, this lower will lock the bolt to the rear.

The complete lower comes with a lower parts kit that includes a 6.5-ounce heavy buffer, mil-spec six-position carbine buffer tube, GI Trigger Group, and .308 WIN carbine recoil spring.

5. Rainier Arms 9mm Billet Receiver Set – Best Upper and Lower

Pros

• Upper and lower sold together
• Tension screw for a perfect fit
• Compatible with 9mm, .40 S&W, and .357 Sig

Cons

• Proprietary pattern

Want to make life easy? The Rainier Arms 9mm Billet Receiver Set includes both upper and lower receivers to give you a head start on your build.

Be advised that these use a proprietary Rainier Arms design, so you can’t mix and match them with other uppers and lowers.

The set comes with a tensioning screw to fine-tune a snug fit between the upper and lower.

Like the Angstadt Arms lower, this one accepts 9mm, .40 S&W, and .357 SIG factory Glock magazines, as well as aftermarket Glock 9mm double stack mags.

It also uses a flared magwell and threaded bolt catch screw. Oh, and you also get last round bolt hold open for empty magazines.

The upper has A4-style feed ramps, an ambidextrous bolt release, and a spacious ejection port.

Other notable features include a threaded retaining screw for the takedown pin, a zinc-plated extractor, and compatibility with a short-throw safety selector.

6. 80% Arms AR-9 80% Lower Receiver – Best Unfinished Lower

Pros

• No FFL needed
• Available in several finishes
• Flared magazine well

Cons

• Labor intensive

If you’re looking for an 80% lower, 80% Arms has your back with the AR-9 80% Lower Receiver.

Since it’s legally a work in progress, vendors can ship it to your home — no FFL needed.

That, in turn, means that you have to have the equipment to do so. Fortunately, that’s just a router and a power drill. 

Pick up a jig to help you with hole placement. We put together a list of jigs that we recommend.

Anyway, back to the receiver itself. It’s CNC machined from a solid piece of aircraft-grade billet aluminum for durability and strength. You can get it with a black, FDE, bead-blasted, or raw finish. 

It’s Glock magazine-compatible and has a flared magwell for quicker, smoother loading. An oversized trigger guard provides plenty of room for gloves. 

The rear takedown lug pocket is already completed, and the lower is designed for mil-spec compatibility. The bolt catch hole and hole for upper receiver tension adjustment are both threaded.

Fire/safe markings are already engraved and the lower is designed to work with an upper receiver that features last round bolt hold open.

And it comes with a lifetime warranty.

Catch all of Johnny’s thoughts on the 80% Arms setup in the full video review below!

9mm Lower vs. 5.56/.223 Lower: What’s the Difference?

Let’s talk about how a 9mm lower is different than a standard 5.56/.223 lower.

For one, 9mm ARs use a blowback system rather than a direct impingement or piston gas system like you’ll find on a standard AR-15.

Because of this, 9mm lowers come with a pre-installed ejector since they require a smaller fire control group. It’s that fin-looking thing behind the magazine well.

The other major difference is that 9mm lowers feature a different magazine well and mag catch/release. They’re set up to work with either Colt or Glock magazines.

Both work well, but you can’t mix and match magazines so if you already own a bunch of one kind, stick with that.

Nowadays, almost everything is Glock-based.

There are a couple of other things to keep in mind when choosing a 9mm lower.

Lowers can be either come stripped or fully assembled.

A stripped lower includes the receiver itself and minimal or no other parts and hardware. You’ll need to buy the little bits and pieces individually or as a lower parts kit (often labelled as “LPK”).

But don’t worry, the ejector and mag release are almost always installed at the factory.

Stripped receivers give you the room to hand-pick every single part of your lower assembly for the ultimate custom feel. Check out our guide to assembling an AR lower for some tips.

A fully assembled or complete lower will come ready to shoot as soon as it’s attached to a compatible upper assembly with everything installed.

Fully assembled lowers require far less work and typically cost less than buying parts individually. On the other hand, don’t expect them to include high-end components.

Why Trust Pew Pew Tactical

This builds on the original article by former PPT author and freelance editor, Megan Kriss. Megan is an avid shooter and researcher with a background in linguistics. She uses her creative and analytical skillset to write articles for the outdoor space. 

Editing this article is Pew Pew Tactical Freelance Editor Scott Murdock. Scott is a Marine Corps veteran and earned his Expert Rifle and Pistol badges while in service. In addition to editing articles for Pew Pew Tactical, he also writes for several gun industry publications, including Task & Purpose, Free Range American, and Outdoor Life. He, too, has reviewed enough guns and gear to know what to recommend to readers when it comes to choosing 9mm lowers.

Rounding out the editorial team for this article is Editor-in-Chief Jacki Billings. Armed with a bachelor’s degree in Mass Communications and a member of the Society of Professional Journalists, ACES: Society for Editing, and the Professional Outdoor Media Association, Jacki runs our experienced team of expert writers and editors. She has worked as a media professional for over 20 years and has specialized in gun media for almost 10 years. As Editor-in-Chief, she uses her expertise to set testing protocols and editorial standards across the site.

Final Thoughts

While our list by no means covers all 9mm lowers on the market, these are some of our favorites with a wide range of price points and degrees of completion.

With a little help from one of the 9mm lowers on this list, you’re just steps away from completing the AR pistol or PCC of your dreams.

As for choosing parts themselves, to find an upper to go with one of the lowers here, be sure to check out the Best 9mm Uppers.

Now tell us more about your 9mm setup in the comments below. Ready to start building? Check out our guides for assembling lower and upper receivers, as well as our complete AR-15 parts list to help you make sure you’ve got everything you need!

Latest Updates

October 2024: Added more details to product selections and provided supporting content.