Building your own gun can be incredibly exciting! Once you’ve narrowed your choice down to a 9mm AR, you will need to choose a lower. A lower is the nickname for a lower receiver and it houses important components of the gun like the trigger and the hammer.
Choosing the right lower for your gun is a big task, but once you understand what you’re looking for, it won’t be so daunting. Read on to learn about why you should buy a 9mm lower to build the gun of your dreams.
Best 9mm AR Lowers
- PSA PX-9 Forged Complete Glock-Style MOE Lower
- PSA 9mm Classic Colt-Style Pistol Lower
- CMMG MK9 9mm Stripped Lower Receiver
- CMMG AR-15 9mm Dedicated Lower Receiver
- Rainier Arms 9mm Billet Receiver Set
- Angstadt Arms UDP-9 Complete Pistol Lower w/ Maxim Brace
- Foxtrot Mike Products AR-15 FM-9 9mm Billet Lower Receiver Stripped
- Quarter Circle Ranger (GSF) Lower Receiver
PSA PX-9 Forged Complete Glock-Style MOE Lower
This lower accepts 9mm Glock-style magazines and works with Palmetto State Armory’s 9mm Hybrid uppers. It has black Magpul MOE stock, a 6 position Buffer tube, and a Magpul MOE black Grip. It is a great entry-level lower.
- For use with Glock-style magazines
- Works with PSA’s 9mm Hybrid uppers
- Assembled with PSA’s lower build kit
PSA 9mm Classic Colt-Style Pistol Lower
This 9mm lower is designed for Colt-style magazines. It comes fully assembled. It is hard coat anodized and designed to be used with Palmetto State Armory’s 9mm Hybrid uppers. The lower has an Aluminum pistol buffer tube, a sling loop latch plate, and an A2-style Grip.
- For use with Colt-style magazines
- Hard coat anodized
- Aluminum pistol buffer tube
CMMG MK9 9mm Stripped Lower Receiver
The CMMG MK9 9mm Stripped Lower Receiver uses Colt magazines. It has some specifications already installed like the feed ramp, bold hold open, and ejector. They have been specifically engineered by CMMG to work seamlessly and be reliable. It is made of forged aluminum and is hard coat anodized, but also has a Teflon coat on top.
- Forged Aluminum
- Includes extended bolt catch, ejector, and feed ramps
- Accepts 9mm Colt magazines
CMMG AR-15 9mm Dedicated Lower Receiver
This is a semi-automatic lower receiver that accepts Colt or modified Uzi-style magazines. It comes with an ejector, bolt catch, and feed ramp. It won’t look like a conversion, because it’s not. Everything has been cut to final dimensions. Customize with the buffer/spring, buttstock, and trigger group that you love.
- AR-15 make
- 7075 T6 aluminum billet
- Hardcoat anodized and then Teflon coated
Rainier Arms 9mm Billet Receiver Set
The aluminum used on this lower is 70% stronger than the common aluminum used on most lowers. It is finished with an anodized Mil Spec hardcoat. The Rainier billets have a high reputation in the industry. This receiver takes Glock mags. It has a flared magwell and includes a tensioning screw. It has a flared magwell.
- A4 Feed Ramps
- Threaded bolt catch screw
- Ambidextrous bolt release
Angstadt Arms UDP-9 Complete Pistol Lower w/ Maxim Brace
This pistol lower is complete and ready to go. It includes last round bolt hold open. It has a stabilizing brace. It includes a flared magwell so reloads are quicker. Its trigger guard is oversized. It will work with any mil-spec upper receiver.
- Last round bolt hold open
- Threaded bolt catch screw
- Comes complete
Foxtrot Mike Products AR-15 FM-9 9mm Billet Lower Receiver Stripped
This is a carbine of pistol caliber that takes Glock magazines. It is completely stripped and will take any standard mil-spec AR015 component. It is a must-have if you are building a novel PCC. It comes with last-round bolt hold-open.
- AR-15 Make
- 7075 T6 billet aluminum
- Lifetime warranty
Quarter Circle Ranger (GSF) Lower Receiver
This lower receiver comes with proprietary parts, like the ejector, magazine catch, and LRBHO assembly. It uses Glock mags. It is engineered with 7075-T6 aluminum. It has a threaded bolt catch pin. It is 12 oz stripped.
- Type III hard coat anodizing
- Last round bolt hold open on empty
- Works with mil-spec perimeters
What’s So Special About 9mm AR Lowers?
How a 9mm Differs From the Standard Model
To start, 9mm setups utilize a blow-back system instead of a gas system like you would discover on the typical AR-15. Due to this, they include pre-installed ejectors because they need a tinier fire control group. They also have a different mag well, catch, and release, which is either in Colt style or in Glock style. Be sure to know which one you want when you’re choosing your lower.
This is why building your own gun is so important. You have to learn about all the different parts of a gun and how they work. A 9mm AR lower will be a great starting place for your gun-building journey.
Stripped vs Fully Assembled
A stripped lower has the receiver along with few or no hardware and parts. You can buy the rest in a lower parts kit or individually. But the mag release and ejector nearly always come installed. Stripped lowers let you completely choose each piece so it is entirely customized.
A fully assembled lower is also known as a complete lower. All it needs in a complete upper and it’s prepared to shoot. While complete lowers are easier and cheaper, they aren’t as high-quality.
Choosing a stripped lower or a fully assembled lower is a huge decision. It changes hours and hours worth of work, and along with that, knowledge. 9mm AR lowers are wonderful because there is one for everybody- stripped or assembled.
Durability
The first thing to look for is durability. You want to see grade 7075 aluminum. It is incredibly durable as well as lightweight. Along the same lines, you want a finish that is corrosion and rust-resistant. Humidity, snow, or rain could all ruin a gun that doesn’t have a finish like this. A hard coat anodized finish will do the trick. Stainless steel, parkerizing, nickel boron, or some name brand coatings will also work.
9mm AR lowers tend to be very high quality, so you won’t have to worry too much about durability. This is one of the big pros of using a 9mm AR lower. They are nearly all built up to spec.
Glock Magazines vs Colt Magazines
It is important to think hard about what kind of magazine you want to use with your AR9. You can’t mix and match Glock and Colt parts. You need to choose a lower based on the magazine you want to use.
Colt magazines are double feed whereas Glock mags are single-feed and harder to load without the use of a tool. Colt mags are made of carbon steel and can rust. Glock mags are polymer with reinforcement of stainless steel, and don’t rust. Glock magazines are very common, whereas Colt mags are more rare.
Something great about AR lowers is that you get this choice. Glocks and Colts both have their pros and cons. While building your gun, you get to choose which type of magazine you would like to use.
Knowing Your Build
It is very important to know your build, especially if you are a new gun owner. If you build the gun yourself, you will be completely familiar with it. You will know exactly how all the parts work and go together to complete a full machine. This is especially important for beginners because it will help them understand guns more.
By using a 9mm AR lower, you will have the perfect starting point to learn about your build. Picking out your lower is the first step to deciding what kind of build you want to do.
Self-Reliance
If your house needs something to be fixed, you will probably opt for trying to fix it yourself instead of outsourcing the work. A gun is the same thing. It will save you money and hardship if you modify the gun to your liking from the very beginning.
Knowing how your gun works lets you modify as you please without needing the help of someone else. You can work at your own pace to build the weapon of your dreams. If you want to keep interchanging pieces, this can become expensive in the long run.
Although it can be overwhelming to try to build a gun as a beginner, it will actually give you a big leg-up because you will fully understand how the weapon works. Take your time so that you don’t miss anything.
The lower that you use will greatly inform your experience building your gun. Choosing the right 9mm AR lower will set you up for success in your journey to self-reliance.
Technology
With the coming of the internet, so along came new ways of building your own gun. While you might think of drilling, metal work, and gunsmithing when you think of building a gun, there is now a new way of building parts: 3D printing.
3D printed guns are equally legal. Any laws that pertain to guns you build yourself also apply to 3D guns. The laws are all the same federally but vary from state to state, so if you plan on printing any parts for your lower, be sure to check state laws first.
Choosing the right lower will allow you to use 3D printed parts to further put yourself in control of your gun-building experience. Imagine putting parts you’ve printed yourself into the perfect 9mm AR lower!
Sporting
ARs are great for competition or for hunting small game. There is a myth that ARs are useless when it comes to sporting, but it is just a myth. They can hunt anything from coyotes to foxes to prairie dogs to squirrels. They are nearly better than any other gun at this.
The lower plays a big role in this. It holds all the key components that make AR9s so great for sporting. With the right lower, you can build a great sporting gun.
Shootable
ARs are very accurate shooters. Using your AR lower, you can adjust things like the size of the grip and length of the pull. When you’re precision shooting, you’d rather not disrupt your position once you’re locked and loaded. The AR eliminates even the need to cycle an action like with a bolt-action rifle.
The recoil on ARs is moderate and its follow-up shots are fast.
The ability to custom-pick an AR lower lets you fully customize the gun to your liking, which will greatly improve shootability. Building your own gun is a great way to make a gun that is highly shootable for you.
Size and Weight
Using the AR lower that you choose, you can make your gun as big or small as you want. It is typically a short, compact gun, perfect for self-defense. The lower receiver is partially what keeps the weight down, so keep that in mind when choosing. Combined with the shorter barrel and lighter ammunition, the AR9 is much lighter than the AR15.
Depending on how big you want your gun to be, you can choose a lower that fits all your needs. If you just want a big gun and don’t care about weight, go for the biggest option out there. If you want something lightweight and compact, that’s available too. The world is your oyster when it comes to AR lowers.
Are There Any Downsides to 9mm AR Lowers?
Power
At maximum speed the 9mm is travelling around 1200 ft/s. This is a large disadvantage to building a 9mm AR- the power is not extreme. But depending on what you’re using the gun for, this may not be an issue.
When you’re putting so much time into building a gun, you want to be sure that it’s the right gun. Think hard about whether speed is important to you. If you’re okay with 1200 ft/s, then keep looking for the right AR lower.
Accuracy
The 9mm is very accurate at distances shorter than 100 yards. However, the bullet will slow down and begin to drop anywhere beyond 100 yards. This limits your range and the bullet drop really puts you at a disadvantage. This means your AR lower will not produce a highly accurate gun.
Unfortunately, which AR lower you choose won’t really impact how accurate your gun is. So you can’t fix this problem just by choosing the right lower. But if you want a 9mm AR this just comes with the package.
Price
Building your own AR is sometimes cheaper than buying a stock gun, but it can easily become way more expensive if you keep buying add-ons, competition-grade pieces, or if you keep adjusting your plans while building. Planning ahead of time will make sure you have a budget for your project.
AR lowers can get pricey. It’s possible to build a good gun, even on a budget. There are great lowers out there at reasonable price points. But if you’re not careful, you can spend more on a lower than you would on a whole gun.
Not a Toy
Building an AR can be rewarding, educational, and fun. But it is also a powerful and potentially dangerous gun that needs incredible attention to detail and extreme patience while assembling. Everything needs to be fit precisely. If you have any question about how to put something together, you need to go to your local gunsmith. If you’re not careful, you or someone else can get seriously injured.
