The AR-15 is one of the most adaptable rifle systems around. And if you’ve read our earlier articles on them, you already know that they can be tailored for a wide range of applications. With this adaptability, enthusiasts can build their own rifles instead of buying them complete.
However, building an AR-15 from individual components requires some careful thought. And this is especially true when it comes to picking out a lower receiver. AR-15 lower receivers are the foundation of your rifle build, and there are many brands and options to consider. Although choosing just one can be tough, we’re here to guide you through what to look for.
Types of AR-15 Lower Receivers
Like the upper receiver, AR lower receivers are available in several unique configurations. These include stripped and complete, forged and billet, and lastly, ambidextrous and non-ambidextrous.
Stripped and Complete Lowers
| Stripped Lowers | Complete Lowers | |
|---|---|---|
| Included Components | Lower receiver only, unless it’s designed to use specific components | Completely assembled with all core AR-15 lower parts, as well as other components (dependent on model) |
| Build Requirements | Requires an AR-15 lower parts kit and tools to finish | No assembly needed; ready to be mounted to an upper |
| Cost | Around $50 to upwards of $250, depending on the make and model | Around $200 to upwards of $1,000+ depending on the make and model |
| Customization | Maximum flexibility as they’re built entirely to your specification | Less initial customization, though they can be upgraded later |
Forged vs. Billet
| Forged Lowers | Billet Lowers | |
|---|---|---|
| Manufacturing Process | Produced by forging aluminum into shape, creating a strong, simplistic design | Produced by milling an aluminum block into shape, allowing for more unique designs and features |
| Weight | Lightweight | Marginally heavier than forged |
| Durability | Exceptionally strong, especially when made from aluminum alloys like 7075-T6 | Not as strong as forged lowers, but still incredibly durable |
| Features | Usually basic; specific features like ambi bolt catches and flared magwells are less common | Often include more specialized features; manufacturing processes make it easier to include features like ambi controls and folding mechanisms |
Ambi vs. Non-Ambi
Originally, the AR-15 was designed for right-handed users, as they make up the majority. But new production technology has made ambidextrous lowers, and controls, more common. Such lowers can come with ambidextrous mag releases, and bolt catches giving users total control of their rifles.
Technically, every lower is ambidextrous to a degree. Ambi mag releases can be added to any lower that’s compatible with mil-spec components. But ambi bolt catches can’t always be added to them. Many aftermarket options require the lower’s bolt catch channel to be milled out, allowing it to drop in. This needs to be done by a gunsmith, so it’s not always an accessible choice. Because of this, there are several brands making ambidextrous lowers that come with ambi bolt catches. Although they cost a bit more than standard ones, they’re worth it if you’re left-handed.
Factors to Consider when Choosing a Lower Receiver
Quality and Durability
A lower’s quality and durability are particularly important. We recommend looking for one made of 7075-T6 aluminum. It’s lightweight and incredibly durable, making it great for all AR-15 builds. Some are made from 6061-T6 aluminum, which was used more in the past. While strong, 7075 outclasses it in just about every way. So, unless you’re building a historic clone rifle, stick with 7075-T6.
Price
The prices of lowers varies depending on their brand, features, and materials they’re made of. As far as affordability goes, mil-spec lowers are where it’s at. They’re all built to the same mil-spec standard, so they all function virtually the same. And since they’re easier to produce, they’re more affordable.
Billet lowers are, comparatively, more expensive. The added time needed to mill in specialized designs, controls, and features drives their price up. But regardless of whether you opt for a forged or billet lower, keep in mind that ambidextrous options usually cost more than standard ones.
AR-15 Lower Receiver Brands
With so many AR manufacturers around, it can be a challenge to choose one. So, to help get you started, we’ve gathered a list of top brands to consider.
Aero Precision
Aero Precision lower options are always a solid choice. Their Gen II stripped lower receiver is a great choice with a mil-spec design, but they have non-mil-spec forged lowers too. One such is the M4E1. It has sleeker aesthetics than mil-spec lowers, added laser engravings, and it’s available in multiple colors, making it one of their most popular options. Plus, they’re compatible with all core AR components.
Aero Precision also has several complete variants of each lower. They can come outfitted with either mil-spec components or upgraded ones like enhanced triggers and Magpul furniture. Their stripped lowers can range anywhere from around $120 to upwards of $150+, while their complete options are typically found around $275 to as much as $400+, depending on the package.
Sons of Liberty Gun Works
Sons of Liberty Gun Works has had quite an impact on the firearms industry. Their mil-spec stripped lower is a solid foundation for all AR builds, making it one of their most popular. However, new to their lineup is their billet lower receiver. It was made in collaboration with Forward Controls Design and was made specifically to match their ambidextrous components.
SOLGW currently offers complete lowers through select dealers. They’re built around their mil-spec lowers and come outfitted with enhanced trigger groups and controls. Plus, they’re available with mil-spec, Magpul, or B5 Systems furniture. Right now, you can find their stripped lowers priced around $140 to $300+. And their complete options are priced around $400 to upwards of $650+.
Bravo Company Manufacturing
Bravo Company Manufacturing, better known as BCM, is one of the most respected names in the industry. As such, their lower receivers are highly sought after for their high-quality construction. BCM doesn’t offer many stripped lower receivers, but they have several complete ones.
Each lower is made from forged 7075-T6 aluminum and come equipped with parts commonly found in BCM’s AR-15 lower parts kit packages. Some may include their Gunfighter Mod 0 stock, while others come with the Mod-1 SOPMOD stock. BCM is a premium rifle and parts manufacturer, so their lower receivers can cost anywhere from around $350 to $450+.
Radian Weapons
Radian Weapons is renowned for their lower receivers. They don’t offer any complete lowers, but their A-DAC lower is ideal for anyone seeking quality. The A-DAC (Ambidextrous Dual Action Catch) is milled from 7075-T6 aluminum and is ambidextrous.
Its unique dual action catch system allows you to use its controls on either side. And it’s also available in multiple colors. Like SOLGW and BCM, Radian Weapons is another premium manufacturer. As such, their lowers come with a premium price of around $515.
Conclusion
It’s critical to know what to look for when choosing a lower. If you like customizability, stripped lowers are the move, although they do come with the caveat of having to build them yourself. But, by having your own choice AR-15 lower parts, the sky is the limit. For simplicity, complete lowers are the move, as they’re ready to use, but limit your ability to customize its components. Either one can be a great pick, but it all depends on what works best for you.
Ultimately, there is no one right answer. Whether you opt for a complete or stripped lower, if it compliments your needs and preferences, you can’t go wrong with it. Both have their benefits, and if you respect and understand them, you’ll be fine. No matter which you go with, our guide, “Tools for Building a Rifle,” covers what you’ll need for future upgrades and field repairs.
