At a Glance: Our Best AR-15 Lower Parts Kits
- OUR TOP PICK: CMMG lower parts kit
- Geissele standard lower parts kit
- BEST BUDGET OPTION: Bravo Company enhanced lower parts kit
Comparison of the Best AR-15 Lower Parts Kits
| PRODUCT | DETAILS | ||
|---|---|---|---|
 Our Top Pick | CMMG lower parts kit |
| View Latest Price |
 Best Seller | Aero Precision Enhanced Lower Parts Kit |
| View Latest Price |
 Best Overall | Geissele standard lower parts kit |
| View Latest Price |
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Best AR-15 Lower Parts Kits in 2021
The Best AR-15 Lower Parts Kits have multiple things in common. They come with high-quality components, and you do not need to worry about pins not fitting, or quality control problems emerging later on. Buying a kit from a reputable manufacturer helps guarantee that you’re getting a quality, reliable product.
Our guide to the top AR-15 lower parts kits
Here’s our list of the best AR15 lower parts kits on the market today. You’ll find a variety of options in the components they include. Whether you need some specific parts for a repair or you are building your own AR 15 from scratch, we’ve got you covered. Some have fire control groups and pistol grips, some don’t. Whatever you need in an LPK, you’ll find it below.
CMMG Lower Parts Kit
The CMMG Lower Parts Kit comes with everything you need to complete or rebuild your AR 15. The kit has high-quality components that work together seamlessly to ensure the operation of your rifle is smooth and accurate. The kit comes organized for easy assembly packaged in color-coded bags, so you know what each piece is and where it goes without opening the bag.
This kit comes with a molded-polymer A2 pistol grip and a mil-spec trigger that gives you a conventional single-stage, 6 to 6.5 pound pull. That’s equivalent to a service rifle. The kit comes with an A-2 style hammer that is compatible with most lowers.
The kit is perfect for basic builds and upgrades with longer pins that are easy to install and remove. The trigger pull is smooth and the safety offers a very smooth and positive operation. The spring that comes with the safety is extremely stiff, making it difficult to install but very effective after installation.
Pros
- You will receive a molded A-2 pistol grip.
- The kit comes with everything separated into color-coded bags.
- The pins in the kit are longer than average to make installation easier.
Cons
- The bolt catch roll pin is oversized, making installation a challenge.
CMMG Gun Builders Lower Parts Kit
CMMG is a family-owned company that focuses on black rifles and their components. They aim to offer top quality at an affordable price. Unlike the complete lower parts kit listed above, this one DOES NOTE include the fire control group, meaning the trigger and hammer assemblies, or a pistol grip. That makes it perfect for those who need specific parts for a repair job or for those who are building their own modern sporting rifle but want to pick their own trigger and pistol grip.
As you might expect, all components included meet or exceed military specifications, meaning you get fantastic durability and reliability. This is backed up by CMMG’s lifetime quality guarantee. Every component is made in the USA.
The precision tooling used in manufacturing produces parts with a perfect fit. The compatibility is outstanding, with components sized just right to fit the widest range of lowers. The selector switch especially is firm and crisp. Dimpled take-down pins offer easier function. Like the model above, this kit comes with parts separated and labelled to help you keep things organized and know where everything goes.
Pros
- Packaging separates and labels the components
- Great machining and sizing of all components
- Excellent value for money
- Safety selector has an outstanding design
- Compatible with most AR 15 lowers
Cons
- Does not include a pistol grip, trigger guard, or fire control group
Geissele Standard Lower Parts Kit
The Geissele Standard Lower Parts Kit comes with everything you need to rebuild or complete your lower receiver except the grip and fire control group. There are eighteen different parts in the kit to ensure your lower functions properly and works at its best. It may seem strange to order a parts kit from Geissele that doesn’t include a fire control group since that’s what they are famous for. This kit gives you the flexibility to select the fire control group that works best for you while enjoying Geissele’s world-class quality with your other components.
The Geissele kit comes with a world-class Posi-lock safety which gives you great, tactile feedback to feel when it is in the safe and firing positions.
The Geissele Lower Kit DOES NOT come with a grip so you will have to choose one separately if you are building your own AR15. This is one of the highest quality AR15 lower parts kits on the market. All components are made and finished with the best materials.
Pros
- The Posi-lock safety gives you a tactile sensation to let you know what mode it is set to.
- The kit uses top-quality steel for all the components.
- Includes 18 different internal components.
Cons
- Does not include a grip
Bravo Company Enhanced Lower Parts Kit
The Bravo Company Enhanced Lower Parts Kit includes enhanced parts to get your AR working smoothly. It includes twenty-seven different components. All components of the kit adhere to mil-spec quality standards, which ensures high-quality materials and machining. The BMC kit comes with an upgraded PNT trigger assembly, with a Mod three pistol grip and an enhanced trigger guard.
Many of the components in this kit have been finished with nickel Teflon, an aerospace coating that guarantees long-term usability and corrosion resistance. The trigger is electroless nickel plated. That process takes out all the grit, giving you an incredibly smooth trigger pull. Precision machining helps make this AR-15 lower parts kit a reliable long-term investment. All the surfaces, such as the sear engagements in the fire control group, are hand polished guarantee smooth operation.
The bolt catch and safety selector meet military specifications and are machined using a three-stage heat treatment process to harden them and resist wear. A phosphate finishing helps with corrosion resistance and increases the lifespan of the components.
Pros
- Polished nickel and Teflon finishes ensure durability and smooth operation.
- All the components are mil-spec for cost-effective reliability.
- The pieces are corrosion-resistant.
Cons
- The kit is not cost-effective.
- The grip could be more ergonomic.
Aero Precision Enhanced Lower Parts Kit
The Aero Precision Enhanced Lower Parts Kit comes with a Magpul MOE grip and billet trigger guard. It includes twenty-eight different pieces to help you fully outfit your AR. All the components are mil-spec and come with corrosion-resistant coatings to give you durability and smooth operation. Magpul AR 15 components are some of the most respected on the market and the pistol grip included with this kit is no exception. The billet trigger guard is also a nice touch.
Together, the components of this kit weigh 8.1 ounces. Manufactured in the United States of America, the Aero Precision Kit comes ready to install with the highest quality components. The components are compatible with any standard AR 15.
Pros
- Includes Magpul MOE Grip and Billet Trigger Guard
The pieces are corrosion-resistant. - This AR 15 lower parts kit is cost effective and high-quality.
- This kit is made in the USA.
Cons
- Some components may require fitting.
Strike Industries AR Enhanced Lower Receiver Parts Kit
The Strike Industries AR Enhanced Lower Receiver Parts Kit is ideal for a completely new build or an update to your current AR 15. The kit comes with all the quality components you need to build out your AR. The kit does not come with a pistol grip.
The included trigger gives you a smooth, 5.5 pound pull and a crisp break. The components come ground and polished to give you the smoothest possible surfaces, cut to precision to help improve operation without sacrificing safety and reliability. The kit features twenty-seven different pieces from enhanced levers and catches to bolt catch springs and roll pins. This is a great-value lower parts kit that is very easy to install.
Pros
- The kit includes a trigger with a 5.5 pound pull.
- Each component is precision cut and has polished surfaces for smooth operation.
- The kit provides you with everything you need to upgrade or update your AR 15 lower.
Cons
- Some components may require fitting.
- Components come unlabeled, so you have to know where they go
- Pistol grip not included
What Should You Look for in an AR-15 Lower Parts Kit?
There are a variety of options to choose from in AR15 lower parts kits. For example, some come with or without a fire control group and some come with or without a pistol grip. Before you purchase an AR15 lower parts kit, make sure you know what components you need for your rifle build. For example, you may want to purchase a specific model of a fire control group or AR pistol grip separately.
With or without a Pistol Grip
If you are getting a kit for repairs, you probably don’t need a pistol grip. If you are building your own AR, consider whether the pistol grip options that come with lower parts kits fit your needs or whether you want to buy one separately. You have a lot to consider among pistol grip options. They are usually made of polymer, but specific features vary, like finger notches, grip angle, texture, diameter, and whether or not they have a storage compartment.
Often, a parts manufacturer like PSA will include a pistol grip from a separate, well-respected brand like the Hogue AR-15 Pistol Grip, so you have some great options in pistol grips that come as part of a kit. Most will be mil-spec, which is what most shooters are used to. If that works for you and you don’t want to pay the extra shipping for some specific pistol grip model, just go for a lower parts kit that includes one.
We did a full review for you on the Best Pistol Grips for Your AR-15 here.
Quality Manufacturing
A lower parts kit should have precision-machined components made of quality steel with advanced finishing techniques. Not all components require a finish, but those that do should have something like nickel boron or teflon. Most manufacturers will advertise the testing and quality control methods employed in manufacturing their components. These include magnetic particle testing and high-pressure testing, which can and should both be carried out on the same component.
Corrosion Resistance
This goes back to the material and finishes used to manufacture the components of the lower parts kit. Besides quality alloys of steel, good finishes like Teflon and nickel boron, the reputation of the manufacturer is also a good indicator of corrosion resistance. Some components can also be chromed for a lifetime of corrosion resistance.
Components That Come in an AR-15 Lower Parts Kit
Some kits come with everything your lower receiver needs besides the receiver body itself. Some come with everything except the receiver, stock, and buffer tube. The total number of components is 33 items. Some also exclude the fire control group. Otherwise, you’ll find parts kits that just include the most commonly lost components or ones that just include all the springs or all the pins needed for a lower receiver.
Here Complete List of Possible Components in an AR-15 Lower Parts Kit
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Final Thoughts
No matter what you’re looking for in an AR15 lower parts kit, we’re sure that you’ll find the perfect option for you above. All of the options we have listed are from well-established and highly respected brands. Manufacturing may be outsourced, but they know where to source components that they can be proud of putting their name on. As with so much about black rifles, the options are really endless.
The Best Pistol Grip for AR-15 and AR-15 Lower Receiver Trigger Guards if you are looking for an outstanding option in either of those to finish off your AR 15 build. Building your own rifle can be a thrilling experience when you know that you are using the best components for you. Have fun and shoot safe.
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