Best AR-15 Lower Parts Kit

An AR-15 lower parts kit is a package of components for the lower half of an AR-15. The kit typically includes a hammer, magazine catch, trigger, safety, grip, and the buffer assembly, which can contain as many different pieces. Getting the Best AR-15 Lower Parts Kit is important.

Lower parts kits are designed to be an easier and more cost-effective way to acquire the components necessary to build or repair an AR-15.

The kits usually come in color-coded bags to organize related parts and for easier assembly. Quality is an important factor when choosing a lower parts kit, as low-quality parts can quickly break down and fail.

High-quality lower parts kits are designed to ensure smooth operation and are best for first-time lower receiver builders.

The best AR-15 and AR-10 lower parts kits

CMMG AR-10 Lower Parts Kit

The CMMG AR-10 Lower Parts Kit includes the following components: a molded-polymer A2 pistol grip, a Mil-Spec trigger with a single-stage 6 to 6½ lbs service rifle pull, takedown pin detents, takedown pins, bolt catch, bolt catch plunger, bolt catch roll pin, disconnector, disconnector spring, hammer, hammer pin, hammer spring, magazine catch, magazine catch spring, front pivot pin, front pivot pin detent, rear takedown pin, rear takedown pin detent, selector, selector detent, selector spring, and trigger guard.

Brownells LPK

The Brownells LPK with Geissele is one of the best AR-15 and AR-10 lower parts kits on the market today. It includes a Geissele rapid-fire trigger, a MOE stock, and grip, as well as a buffer tube assembly that’s absent from most LPKs.

The parts come in separate color-coded bags for easy assembly and the trigger guards are made of durable metal. The pivot and takedown pins have heavy-duty steel retainers instead of the brass ones found in other kits, and the trigger guard is made of sturdy material.

The main reason for the increased price is that Brownells has taken the extra steps to provide superior products that offer great value.

They have included premium components such as the Geissele trigger and MOE stock and grip, as well as the buffer tube assembly. Plus, the precision-machined parts are designed to withstand a beating and to fit in perfectly with your rifle. Ultimately, this is a great kit for beginners who are focused more on the experience of the build and don’t need the extra savings or the best possible parts.

Geissele Automatics Lower Parts Kit

The Geissele Automatics Lower Parts Kit is a high quality and utilitarian kit without any extra frills. It includes everything you need to get your lower part operational, except the trigger and pistol grip, letting you choose your own. The parts are precision machined and durable, and the kit is affordably priced. The components are all milspec and are designed to fit a wide variety of mil-spec lowers.

This kit also features lower receivers manufactured to “mil-spec” M16 / M4 dimensions, as well as a fire control system comprising hammer, trigger, disconnector, and pins. Additionally, the kit uses high-quality steel for all the components, and the safeties are crisp and easy-to-use. However, the magazine release button may need hand fitting.

Aero Precision Lower Parts Kit

The Aero Precision Lower Parts Kit is designed to build the M4E1 lower receiver and includes Magpul MOE Grip, a Billet Trigger Guard, and 28 different mil-spec components. The components are corrosion-resistant and made in the USA.

All components are compatible with any AR 15 and weigh 8.1 ounces together. This kit features a molded A-2 pistol grip and comes with everything separated into color-coded bags, the pins being longer than average for easier installation.

PSA MOE Lower Build Kit

The PSA MOE Lower Build Kit includes a Mil-spec MOE stock, grip, trigger guard, and buffer tube, as well as a standard single-stage government-style fire control group with polished contact surfaces, a nickel-coated hammer, and trigger, and Magpul components.

It is designed to build the lower receiver of an AR or a pistol and is compatible with military standards for maximum compatibility. This makes it a great value as it is an ideal option for building a sturdy and reliable lower receiver.

SMLP K2 Mil-Spec Lower Parts Kit

The SMLP K2 Mil-Spec Lower Parts Kit includes the following components: A2 Pistol Grip, Selector Spring, Selector Detent, Bolt Catch Spring, Bolt Catch, Magazine Catch Spring, Magazine Catch Button, Front Pivot Pin, Hammer Spring, Trigger Spring, Disconnector Spring, Hammer, Trigger, Disconnector, Safety Selector, Magazine Catch, Rear Take Down Pin, Buffer Retainer Spring, and Buffer Retainer.

Additionally, the kit includes high-quality nickel-plated pins and detents for a smoother trigger pull and increased durability.

CMC Triggers AR-15 Lower Parts Kit

The CMC Triggers AR-15 Lower Parts Kit includes a molded A2 pistol grip, trigger, trigger spring, disconnector, hammer spring, hammer, bolt catch, bolt catch spring, bolt catch plunger, bolt catch roll pin, magazine catch spring, magazine catch button, selector, selector detent, selector spring, front pivot pin, rear takedown pin, takedown detents, takedown springs, buffer retainer, buffer retainer spring, and an enhanced aluminum trigger guard.

SOLGW Blaster Guts With Liberty Fighting Trigger

The SOLGW Blaster Guts with Liberty Fighting Trigger AR-15 Lower Parts Kit features a set of parts that are designed to be in-spec with strict adherence to MIL-SPEC standards. This includes steel mag buttons, magazine catch, bolt catch and safety selector.

The Liberty Fighting Trigger is built for duty and defensive use, and provides an incredibly smooth trigger pull, always breaking between 6 and 6.5 pounds. Additionally, the kit also features a Mil-Spec B5 Systems pistol grip and no ambidextrous trigger. All components are designed to provide maximum durability and functionality, and are built with strict quality control.

What to consider when choosing an AR-15 lower parts kit

Quality and Fit

When choosing an AR-15 lower parts kit, it is important to consider the quality and fit of the components. The best lower parts kits will feature high-quality and mil-spec components designed to ensure smooth operation. Look for kits with molded-polymer A2 pistol grips, triggers with single-stage 6 to 6½ lbs service rifle pulls, and color-coded bags to organize and simplify the assembly.

Additionally, check the external finish on the parts for smoothness and even application and look for any burs on the metal parts. When installing the lower parts kit, do a quick fit check on each part to make sure it moves freely inside the lower receiver.

Lastly, it is important to do a function check on the lower receiver to ensure the trigger releases the hammer, safety works, and magazine locks into and releases from the receiver easily. Quality and fit are the most important factors to consider with an AR-15 lower parts kit.

Price

The price range for an AR-15 lower parts kit varies greatly depending on the brand and components included. PSA MOE Lower Build Kit offers an affordable option at $129, while Geissele AR15 Lower Parts Kit is on the higher end at $299. Brownells AR-15 Lower Parts Kit w/Geissele 2-stage Enhanced Trigger is also a great choice at $199.

For more budget-friendly options, check out the CMMG AR15 Lower Parts Kit at $69 and the PSA MFT Minimalist EPT Lower Build Kit at $129. Additionally, there are many other kits available, with prices ranging from $9.99 to $149.99.

Features and Options

When it comes to AR-15 lower parts kits, there are a variety of features and options available. Generally, you can expect to find components such as trigger guards, pistol grips, bolts, pins, hammers, detents, springs, and safety selectors in a lower parts kit. The M&P AR-15 Rifle Complete Lower Parts Kit, for example, includes an Enhanced Drop-In trigger and 20 total components built to military specifications.

The Aero Precision Enhanced Lower Parts Kit comes with a Magpul MOE Grip and Billet Trigger Guard, while the Bravo Company AR-15 Enhanced Lower Parts Kit features polished nickel and Teflon finishes for durability and smooth operation. Ultimately, the features and options available for an AR-15 lower parts kit vary but are always built to last and provide you with the best possible experience.

Compatibility

When selecting an AR-15 lower parts kit, there are several compatibility considerations to take into account. The parts in the kit should be designed to fit into the chosen AR-15 lower receiver, as poor fit and finish can lead to sluggish operation or parts not fitting correctly.

Additionally, the parts should be of a high quality and have a smooth finish to ensure smooth operation.

It’s also important to consider the features of the kit, such as the CMMG featuring color-coded bags to organize related parts and for easier assembly, while the Aero Precision kit includes the Magpul MOE Grip and Billet Trigger Guard. Finally, the Bravo Company AR-15 Enhanced Lower Parts Kit offers polished nickel and Teflon finishes which ensure durability and smooth operation.

Overall, when selecting an AR-15 lower parts kit, it is important to take into account the compatibility with the chosen lower receiver, the quality of the parts, and the features each kit offers.

With these considerations in mind, you can find the best lower parts kit for your AR-15 build.

Size and weight

When choosing an AR-15 lower parts kit, size and weight should be considered. The CMMG – AR-15 Lower Parts Kit is smaller and lighter than the other kits, making it ideal for those looking for a smaller and lighter firearm.

The Aero Precision – AR-15 Lower Parts Kit is larger and heavier, making it ideal for those looking for a more robust firearm. The CMC Trigger – AR-15 Lower Parts Kit offers the option of choosing what components to include, so it is great for those looking for a customized firearm.

The KE Arms LLC – AR-15 GI Lower Parts Kit offers mil-spec components for a reliable firearm, and the Brownells – AR-15 Lower Parts Kit 5.56 is designed for 5.56 caliber firearms for those looking for a specific cartridge.

The Geissele Automatics LLC – AR-15 Lower Parts Kit is designed for precision and accuracy, the M&P AR-15 Complete Lower Parts Kit is designed for easy installation, and the Double Star – AR-15 Lower Parts Kit offers corrosion-resistant components.

All of these kits come with unique features and benefits that should be taken into consideration when choosing the best AR-15 lower parts kit for your needs.

Finish

When selecting an AR-15 lower parts kit finish, there are several considerations to take into account. Quality is the most important consideration when it comes to finding the right finish for your lower parts kit.

The fit and finish should be well-made and reliable, with each piece fitting together perfectly. The pieces should also be corrosion-resistant and durable.

Popular finishes for lower parts kits include polished nickel and Teflon, which are both known for their longevity and reliability. Additionally, some kits come with an OEM finish, which is often high-quality and respected.

Finally, some kits come with a molded A-2 pistol grip, which can be a great addition for those looking for a more ergonomic grip. Ultimately, the choice of finish will come down to personal preference and budget, so make sure to do your research before deciding on the best option for you.

Overall, the trigger pull and reset characteristics of an AR-15 lower parts kit will depend on the individual parts kit and its components. Some kits offer enhanced triggers with smooth pulls while others are more basic and offer a conventional trigger pull. All of these kits are great options depending on the intended use of the rifle.

Caliber options

When choosing an AR-15 lower parts kit, there are many caliber options available. The most common options are 5.56 NATO, .223 Remington, .300 Blackout, and .308 Winchester.

Each caliber option has its own set of components and features, so it’s important to consider your needs before making a purchase.

Additionally, some kits come with more than one caliber option, so you can choose the best one for your needs.

Trigger group and safety

When choosing an AR-15 lower parts kit, it is important to consider which type of trigger group and safety you wish to have.

Some lower parts kits come with an enhanced drop-in trigger, while other kits may use a mil-spec trigger that provides a conventional single-stage, 6 to 6.5 pound pull.

An ambidextrous safety selector is also a common feature on enhanced lower parts kits, allowing the user to easily switch between multiple firing modes with ease.

A short throw safety is often included in these kits as well, allowing the user to switch between safe and fire quickly and easily.

Finally, some lower parts kits may also come with a nickel boron finished trigger or trigger that has been upgraded in some other way.

Ultimately, when choosing an AR-15 lower parts kit, it is important to consider the type of trigger group and safety that best suits your needs and preferences.

Stock and Buffer

When building an AR-15, it is important to consider the type of stock and buffer parts kit to use.

The LUTH-AR LLC – AR-15 lower parts kit is one of the best options and includes all the parts necessary to turn a stripped lower into a complete receiver, such as a Fire Control Group, AR-15 stock and buffer system, pistol grip, and trigger.

This kit also includes a standard A2-type plastic pistol grip, a fancier, aftermarket grip, and all the pins-n-springs required for the mil-spec AR-15 fire control components.

For those who are looking for additional functionality, installing a free float quad rail and adding a foregrip and bipod are other options.

When selecting the best LPK for you, make sure it includes a Fire Control Group, AR-15 stock and buffer system, pistol grip, and trigger that are compatible with the AR-15.

This will ensure that your build is as efficient and reliable as possible.

Upper Receiver Build

When it comes to building an AR-15 lower parts kit, there are a few upper receiver build considerations to take into account. CMMG and Aero Precision both offer excellent lower parts kits, but for maximum value and customization, the Bravo Company Enhanced Lower Parts Kit is our top pick.

This kit includes a molded A-2 pistol grip, cost-effective and high-quality pieces, and corrosion-resistant components with polished nickel and Teflon finishes.

When comparing the CMMG AR-15 Lower Receiver Parts Kit and the Aero Precision Enhanced Lower Parts Kit, the CMMG kit includes parts that are separated into color-coded bags and pins that are longer than average to make installation easier.

However, the Aero Precision kit provides corrosion-resistant pieces and also includes a Magpul MOE Grip and a Billet Trigger Guard.

The Bravo Company AR-15 Enhanced Lower Parts Kit is our top pick as it offers the best of both worlds. It has cost-effective and reliable components that are mil-spec, as well as corrosion-resistant pieces with polished nickel and Teflon finishes for smooth operation.

Ultimately, this kit provides the most value, flexibility, and durability for your build.

Build Options

The build options for an AR-15 lower parts kits vary depending on the specific kit you choose. For instance, the CMMG – AR-15 Lower Parts Kit includes an enhanced drop in trigger and great quality parts. On the other hand, the Aero Precision – AR-15 Lower Parts Kit includes Magpul MOE Grip and Magpul Billet Trigger Guard.

Similarly, the CMC Triggers – AR-15 Lower Parts Kit allows you to choose what components to include and is cost-effective and high-quality.

The KE Arms LLC – AR-15 GI Lower Parts Kit is made to meet or exceed military specifications, is color-coded for easy assembly and has a very smooth pull and a clean break.

The Brownells – AR-15 Lower Parts Kit 5.56 is a very high-quality kit and is designed to fit many guns perfectly.

The Geissele Automatics LLC – AR-15 Lower Parts Kit has pins that are sized perfectly and the M&P AR-15 Complete Lower Parts Kit is made from corrosion-resistant components.

The Double Star – AR-15 Lower Parts Kit is an affordable option and the Critical Capabilities LLC – AR-15 Lower Parts Kit is cost-effective. Lastly, the LUTH-AR LLC – AR-15 Lower Parts Kit offers trigger-free components.

Overall, when selecting an AR-15 lower parts kit, it is important to consider your budget, ergonomics, functionality, durability, and what components are included.

Retailers

When it comes to finding the best retailers for an AR-15 lower parts kit, there are several excellent choices. Brownells offers its AR-15 Lower Parts Kit 5.56, which contains all the necessary parts for a lower receiver.

Palmetto State Armory offers its MagPaul MOE Lower Build Kit, which contains all the parts needed to build a complete lower receiver.

CMMG’s AR-15 Lower Parts Kit contains all the components needed to build a lower receiver, as does Bravo Company’s Lower Parts Kit. Geissele Automatics Lower Parts Kit and Brownells AR-15 Lower Parts Kit With Trigger Assemblies offer an enhanced drop-in trigger, plus all the other components needed for a lower receiver.

Finally, Seekins Precision Enhanced Builders Kit and Elftmann Tactical Lower Parts Kit are both excellent options for those looking to construct a lower receiver.

FAQ

What is a Lower Parts Kit (LPK) for an AR-15?

A Lower Parts Kit (LPK) for an AR-15 is a set of parts necessary to complete the lower receiver of a rifle.

It includes all of the components necessary to make the lower receiver function, such as the pistol grip, trigger, trigger guard, bolt catch, disconnector, magazine catch, magazine release button, safety selector, pivot pin, takedown pin, trigger pin, hammer pin, buffer retainer, buffer retainer spring, selector detent, takedown pivot pin, pivot pin detent, takedown pin detent spring, pivot pin detent spring, selector spring, bolt catch spring, disconnector spring, ejection port, and forward assist.

An LPK is necessary to complete the assembly of a stripped lower receiver, and allows shooters to customize their build to their own preferences.

There are a variety of different LPKs available on the market, ranging from complete kits to those that lack certain parts such as the trigger, pistol grip, and trigger guard.

A reliable LPK can make the building process of a rifle considerably easier and smoother.

What is the best Lower Parts Kit (LPK) for an AR-15?

If you’re on the market for the best Lower Parts Kit (LPK) for your AR-15, you’ve come to the right place.

While there are many different kits available, not all of them are created equal. With so many choices, it can be difficult to know which one is the best for your specific needs. That’s why we’ve put together this comparison and evaluation of the top LPKs on the market so you can make an informed decision.

The Aero LPK Parts kit is a great choice for those looking for quality parts and craftsmanship. This kit includes all parts needed for the lower receiver and meets military specifications.

It also pays extra attention to the trigger group and machined billet trigger guard and billet magazine guard assembly that they call “enhanced.”

Stag Arms offers another excellent LPK that is perfect for upgrades or maintenance of your lower receiver. The kit features all parts of a lower receiver, except for the pistol grip, and is known for being reliable and durable. Stag Arms also offers a limited lifetime warranty on its parts.

Finally, those looking for top quality and reliability should consider the AR-15 LPK from CMMG.

This kit includes all parts needed to construct or maintain an AR-15, including an enhanced fire control group and magazine release kit. CMMG also offers a lifetime warranty on their parts.

Ultimately, the best Lower Parts Kit (LPK) for an AR-15 will depend on your individual needs and preferences. Consider the specs, build quality, and reliability of each kit to make sure you get the perfect LPK for your AR-15 build.

What is the difference between an AR-15 and an AR-10 Lower Parts Kit (LPK)?

The AR-15 and AR-10 Lower Parts Kit (LPK) have some significant differences in terms of parts and size.

The AR-15 LPK is for the smaller AR-15 rifle and will include parts such as a Bolt Catch, Bolt Catch Roll Pin, Pivot Pin, Takedown Pin, Buffer, Buffer Spring and Magazine Catch.

The AR-10 LPK is for the larger, older counterpart of the AR-15 and the parts that are not interchangeable are the Bolt Catch, Bolt Catch Roll Pin, Pivot Pin, Takedown Pin, Buffer, Buffer Spring and Magazine Catch.

The AR-10 also has two “patterns” of lower receivers, the most common of which is the DPMS variant.

Quality should also be taken into consideration when choosing an LPK as it usually equates to better durability and functionality of the rifle.

What is the difference between a mil-spec and a precision Lower Parts Kit (LPK)?

The main difference between a mil-spec and precision Lower Parts Kit (LPK) is the overall quality and durablity of the parts.

Mil-spec LPKs are designed to meet military standards, ensuring a certain level of quality. These parts are usually less expensive, but may not offer the best value for your money.

On the other hand, precision LPKs are often more expensive but also offer a higher level of performance and feel. They also come with thicker coatings and may have a heavier trigger pull than mil-spec LPKs.

Additionally, precision LPKs typically come with a 4-40 set screw, which is a must when using an Aero lower receiver. In short, precision LPKs offer higher quality and better performance but come at a higher cost.

What brands make the best Lower Parts Kit (LPK) for an AR-15?

When it comes to finding the best Lower Parts Kit (LPK) for your AR-15, there are a few reputable brands you should consider.

Aero Precision offers a complete LPK, which includes all parts of the lower receiver except for a pistol grip.

This kit is specifically designed to meet military specifications, and it comes with an enhanced billet trigger guard and billet magazine guard assembly.

Stag Arms is another good choice when it comes to LPKs. Their kit includes all parts of a lower receiver and is backed by a limited lifetime warranty.

Another great brand is CMMG, which is well known for their attention to detail and high-quality products. Lastly, Luth-AR is another popular brand offering an extensive line of LPKs, focusing on providing the absolute best quality components available.

When choosing a LPK for your AR-15, make sure to look for kits that have the highest quality materials and parts and come from reputable brands. This will help ensure that your AR-15 will have smooth and reliable operation.

What are the pros and cons of the different Lower Parts Kit (LPK) options?

When it comes to choosing a Lower Parts Kit (LPK), there are many options to consider. Each option has its own pros and cons that should be weighed when making your decision.

One popular choice is the LPK from CMMG. Pros of this option include easy installation, color-coded baggies, extra and convenient parts, and an A2-style hammer and grip.

Its cons include not including a stock and an oversized bolt catch pin that may be challenging to install.

Another option is the Aero Precision Lower Parts Kit. Its pros are that it is all mil-spec, so it will work with most other brands, and it is designed to minimize any headaches that come with doing your own build. Its cons are that it does not include a stock.

Ultimately, the best LPK option is the one that best fits your needs and budget. Be sure to do your research to determine which option is the best for you.

How do I know which Lower Parts Kit (LPK) is compatible with my AR-15?

Knowing which Lower Parts Kit (LPK) is compatible with your AR-15 can be a daunting task, especially when starting from scratch with a bare lower. To ensure that you get the best LPK for your AR-15, follow these simple steps:

1. Know your parts: Before you start shopping for an LPK, familiarize yourself with the various components that make up an AR-15 lower. This includes the pistol grip, trigger guard, trigger, bolt catch, disconnector, magazine catch, magazine release button, safety selector, pivot pin, takedown pin, trigger pin, hammer pin, buffer retainer, buffer retainer spring, selector detent, takedown pivot pin, pivot pin detent, takedown pin detent spring, pivot pin detent spring, selector spring, bolt catch spring, disconnector spring, ejector port, and forward assist.
2. Consider your starting point: If you’re starting from scratch with just a bare AR lower, you’ll need to go for a full kit. However, if you already have a stock and pistol grip, you don’t need to go for a full kit and something like the LPK from Geissele will do.
3. Research and compare: Now that you know the parts that you need, it’s time to do some research and compare the different LPKs available in the market. Take into consideration the quality of the parts and the price to get the best value for your money.
4. Mix and match: Don’t be afraid to mix and match parts from different LPKs as long as they are compatible. As long as the parts fit properly and have the same specifications, you should be good to go.

For example, the Geissele Automatics SSA-E Trigger is a great choice for a lower parts kit for those seeking an upgrade. It has an incredibly smooth 4.5lb pull weight, and is made from the best materials to ensure reliability and performance.

It’s also compatible with most AR-15s, making it a great choice for those looking to build their own AR-15.

What is the difference between an LPK and a build kit?

Lower Parts Kits (LPKs) and Build Kits are both used to build AR-15 and AR-10 rifles, but they have different purposes. An LPK, or Lower Parts Kit, is used to convert a stripped lower receiver into a fully functioning lower receiver.

This kit includes all of the small parts and pieces needed to build a lower receiver, including a pistol grip, trigger, trigger guard, magazine catch, safety selector, pins and springs.

On the other hand, Build Kits contain all the parts necessary to build a rifle from scratch, including the upper and lower receivers.

This kit includes a complete set of parts for the entire rifle, from the barrel to the buttstock, allowing the user to fully customize their rifle to fit their individual needs and desires.

In summary, an LPK contains the parts needed to build the lower receiver of an AR-15 or AR-10 rifle, while a Build Kit contains all the parts needed to build the entire rifle.

How do I properly install a Lower Parts Kit (LPK) for an AR-15?

Installing a Lower Parts Kit (LPK) for an AR-15 requires a bit of technical knowledge, but it is relatively simple with the right steps.

To properly install an LPK, you should first identify the parts you need and make sure you have all the components of the kit. Once you have all the parts, you are ready to begin assembly. Here is a step-by-step guide for installing an LPK for an AR-15:

1. Start by assembling the trigger, safety, and all pins and springs. Make sure to place the parts in the right orientation and be mindful of the springs and pins.
2. Next, install the pistol grip and secure it with a screw and lock washer.
3. Install the trigger guard and the disconnector.
4. Place the magazine catch into position and secure it with the magazine catch spring.
5. Install the magazine release button and safety selector.
6. Place the pivot pin and takedown pin in the right place and secure them with the detents and detent springs.
7. Fit the buffer retainer and the buffer retainer spring.
8. Place the selector spring and the bolt catch spring and secure them.
9. Fit the disconnector spring and the ejection port cover.
10. Complete the assembly by fitting the forward assist.

Now you have your fully assembled AR-15 lower parts kit. Make sure to check all the parts for any signs of wear or damage before completing the assembly.

After the installation is complete, you can proceed to attach the upper receiver to your AR-15 lower.

Once you get your gun squared away grab a suppressor and a suppressor cover and enjoy some range time!