Top-Performing AR-15 Lower Receivers 

Introduction

Time to read: 8.5 minutes

Date: 05/17/23

Are you looking to build your own AR-15 but need help figuring out where to start? In this blog post, we’ll introduce you to the top AR-15 lower receiver options on the market. From forged to billet to polymer materials, we’ll be breaking down what each type of aluminum material does for your lower receiver. 

Plus, we’ll familiarize you with the components of a lower receiver and the importance of each different feature. Get ready to read about the top-performing AR-15 lower receivers from brands like KEarms, Palmetto State Armory, Lewis Machine & Tool, LMT Defense, and Aero Precision. So, let’s get started on building the ultimate AR-15!

What is a Lower Receiver? 

An AR-15 lower receiver is a gun component that houses the trigger assembly, magazine well, and buffer system. It serves as the foundation for the firearm, connecting the upper receiver, barrel, and stock. The only component of the AR-15 that is subject to regulation by the government is the lower receiver, which necessitates a background check and purchases through a registered dealer. 

It also distinguishes the AR-15 from other firearms due to its unique design and compatibility with a wide range of accessories and modifications.

Types of Lower Receivers 

6061-T6 aluminum and 7075-T6 aluminum are the two primary materials that manufacturers use for AR-15 receivers. The latter is almost twice as strong as the former, but it is also more expensive and less corrosion-resistant. Essentially, this means that 7075-T6 aluminum receivers are superior, but they come at a higher cost. 

However, corrosion resistance can be improved with proper anodization. While polymer receivers are an option, they are not as durable as aluminum, although they are easier to work with if you have an 80% lower receiver. We will be talking about all three in this section and giving you the pros and cons of each.  

Forged Aluminum

The most popular type of lower receiver, the forged aluminum. These receivers are made by hammering an aluminum block into the correct shape using a forging press. Once the forging process is complete, the receiver is machined again, beating it to final specifications. 

PROS:

• Durable: Forged aluminum lower receivers are very strong and can withstand a lot of abuse.
• Affordable: Forged aluminum lower receivers are typically less expensive than billet or polymer lowers.

CONS:

• Heavy: Forged aluminum lower receivers are relatively heavy compared to other types of lowers.
• Limited customization: Forged aluminum lower receivers cannot be customized to the same extent as billet or polymer lowers.

Billet

These are made by machining a solid block of aluminum into the shape of a lower receiver. This process allows for a high degree of customization and precision, making billet lowers a popular choice among firearm enthusiasts. 

PROS:

• Customizable: they can be customized with unique designs and features.
• Precise: they offer a higher degree of precision than forged aluminum lowers.

CONS:

• Expensive: they are typically more expensive than forged aluminum or polymer lowers.
• Less Durable: they are less durable than forged aluminum lowers.

Polymer

Unlike the forged and billet options made from aluminum, polymer lower receivers are made from a type of plastic that is reinforced with carbon fiber or other materials. These lowers are relatively new to the market but are growing in popularity due to their lightweight construction. 

PROS:

• Lightweight: they are the lightest type of lower receiver available.
• Affordable: they are typically less expensive than forged aluminum or billet lowers.

CONS:

• Durability: they are not as strong as forged aluminum or billet lowers and can crack or break under heavy use.
• Limited Customization: they cannot be customized to the same extent as billet lower receivers.

When compared to aluminum options, a polymer lower is a feather to a bag of bricks. You may not feel the difference when holding an aluminum lower in one hand and a polymer in the other (roughly a 3-ounce difference). 

When adding the stock, grip, and receiver is when you feel a significant difference. A complete aluminum lower can weigh close to 3 pounds, whereas a polymer lower will weigh closer to 1.6 pounds. 

The Three Types of Anodizing Finishes

Anodizing is by far the most popular finish for ARs and tactical rifles due to its matte black finish, which is where the term “black rifle” comes from. However, the same process can produce a variety of colors, ranging from burnt bronze to OD green, as well as custom looks.  The process for hardcoat anodizing involves coating aluminum with aluminum oxide or purposely applying aluminum rust.

Type 1

Type I anodizing is a softer and less durable finish that’s typically reserved for small, low-wear components. This finish is produced using chromic acid and has a thin finish depth of 0.0001″. Due to its lack of durability, it’s not used on high-wear parts such as AR receivers.

Type 2

Type II anodizing is a thicker coating that’s at least twice as thick as Type I, ranging from 0.0002″ to 0.0006″ thick. It’s produced using sulfuric acid and is a level of protection that can be done at home with safety precautions and an appropriate DIY anodizing kit. This type of anodizing is suitable for parts that undergo moderate wear and tear.

Type 3

Type III anodizing, also known as “hardcoat” anodizing, is the most durable form of anodizing. It uses sulfuric acid that’s cooled to accommodate the higher electrical current, adheres to more exacting measurements, and uses de-oxidizing agents for a precision coat. 

It has a coating thickness ranging from 0.0005″ to 0.003″. This type of anodizing is used for high-wear parts such as AR receivers and military rifles. When you hear “mil-spec anodizing,” it refers to a Type III anodized finish.

Stripped vs. Complete

One of the things you’ll need to decide when building your own AR-15 rifle is whether to go for a stripped or a complete lower receiver. The main difference between these two options is the level of assembly. 

A stripped lower receiver is just the lower receiver itself, without any internal components installed, except for the trigger guard and takedown and pivot pins. In contrast, a complete lower receiver comes with all the internal components already installed, such as the trigger, hammer, bolt catch, magazine release, and safety selector.

The choice between a stripped or complete lower receiver typically depends on your desired level of customization. If you want to have a high degree of control over each component in your build, then a stripped lower receiver is the way to go. 

This option allows you to choose each component individually, including the trigger, buffer tube, and stock. However, keep in mind that this approach requires more time, effort, and expertise to assemble all of the components correctly.

If you’re looking for a more straightforward and faster approach to building your AR-15, then a complete lower receiver may be the better choice. With all of the components pre-installed, you don’t need to worry about assembly or compatibility issues. However, this option provides less opportunity for customization.

Another consideration is cost. Stripped lower receivers are usually less expensive than complete lower receivers since they include fewer components. However, the total cost of the build may end up being higher, as you need to purchase additional components separately. 

A complete lower receiver may have a higher upfront cost, but it can be a more cost-effective option in the long run, as it eliminates the need to purchase additional components separately. Ultimately, the decision to choose a stripped or complete lower receiver depends on your goals, preferences, and budget.

Five Top-Performing AR-15 Lower Receivers

KE Arms KP-15 Complete Lower

The KP-15 is a polymer AR15-style receiver made from injection-molded 30% glass-filled nylon. It incorporates the buttstock, buffer tube, pistol grip, and trigger guard as integral components. This results in a lighter weight, lower cost, and increased production speed compared to similarly configured receivers. 

It is compatible with most AR15 uppers and lower parts kits, and has a flared magwell, improved grip, and winter trigger guard. The SLT/Ambi Lowers include several components such as KP-15 Long Hammer Pin and KP-15 Optimized Ambi 90/45 Selector assembly. 

BLEM PSA AR-15 COMPLETE MOE STEALTH

It is made of 7075 forged aluminum with a mil-spec, single-stage fire control group and Magpul MOE furniture in black. The product may have cosmetic blemishes such as forging marks and scratches, but these do not affect its function. It does not come with a magazine, but it is compatible with all mil-spec AR-15 uppers.

Lewis Machine & Tool Company MARS-L

(Modular Ambidextrous Rifle System)

MARS-L SOPMOD Complete Lower

The LMT MARS lower receiver has ambidextrous controls for the selector, magazine release, and bolt catch and release. It also has an enhanced flared magazine well and ambidextrous magazine and bolt catch mechanisms built into the receiver for ergonomic functionality. 

Additionally, it features a two-stage trigger group, winter trigger guard, ergo grip, QD (quick detach) endplate, and SOPMOD buttstock for increased durability and versatility.

M4E1 Carbine Complete with A2 Grip

The M4E1 Complete Lower Receiver is a great starting point for a custom AR15 build. It includes the M4E1 Lower Receiver with an A2 Grip, as well as a Mil-spec Lower Parts Kit, AR15 Carbine Receiver Extension, and AR15 Carbine Buffer and Spring. The lower is already assembled, but does not come with a stock. Choose your preferred stock and save on the initial purchase. Magpul FDE Cerakote finish

AR15 Complete Lower Receiver w/ MOE Grip & SL-S Carbine Stock

Aero Precision AR15 Complete Lower Receiver with Magpul SL-S Carbine Stock is an ideal upgrade for AR builds. The complete lower comprises AR15 Gen 2 Lower and a Magpul SL-S Carbine Stock. 

The MOE SL-S Stock is a storage-capable version of the flagship Magpul MOE SL carbine stock and a direct replacement buttstock for AR15/M4 carbines. The package includes AR15 Gen 2 Lower Receiver, Magpul MOE Grip, Magpul SL-S Stock, Lower Parts Kit, Carbine Receiver Extension, AR15 Carbine Buffer, and Spring. All parts are pre-installed.

Conclusion

So there you have it! Understanding the differences between forged, billet, and polymer firearms is essential when choosing a top-performing AR-15 lower receiver. Many reputable brands carry everything you need to customize your shooter, and we have confidence that you know what to look for now!

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