So you want to make some modifications to your AR-15? Or maybe you want to start a custom build for the rifle you’ve always dreamed of? Or, maybe you need a minor repair but don’t want to cough up money for a gunsmith? No matter your reason, you’ll need a good lower parts kit.
Let us show you the best kits on the market and explain what to look for in our guide down below.
Comparison of the Best AR-15 Lower Parts Kits
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What’s in a Lower Parts Kit?
Typically, a good lower parts kit will have everything to need to deconstruct and modify the lower pieces of your AR-15 carbine. This won’t allow you to modify everything on the rifle but it will let you either begin the construction of your own weapon or let you make repairs without having to go to an expensive gunsmith.
Your lower parts kit should include:
- Trigger springs, pins, and a trigger
- Hammer springs, pins, and a hammer
- A disconnector and spring
- A bolt catch, and a bolt catch plunger, spring, and roll pin
- A safety selector, detent, and spring
- 2 Takedown detents and springs
- A pivot pin
- A rear takedown pin
- A buffer retainer and spring
- A magazine catch assembly
- A trigger guard assembly
- And a pistol grip
While that seems like a lot, it’s everything you need to start your own carbine build or replace anything that’s out of order. You can make some great custom weapons with these kits, too.
Aspects to Consider Before Buying
Before we show you the top AR-15 Lower Parts Kits, remember to keep these key points in mind before you make any final decisions. These are the factors that make or break good kits.
Get a kit that’s designed to work with the barrel of your AR-15. You won’t have much luck or necessarily produce a stable gun if you get a kit that’s not right for your barrel.
Some kits are more expensive than others. You should always weigh the modifications or repairs you have in mind against their cost from a professional. Sometimes it’s cheaper to get your weapon repaired elsewhere, although this is rarely the case.
Military Spec or Premium
Most military kits are easy to use and produce effective rifles. Premium kits allow for more customization and are usually more expensive. In addition, military kits pay a lot of attention to weight (since they're usually considering the total weight a soldier must lug around).
Lighter kits are easier to use on the go or from anywhere you need, while heavier kits will need to be kept at home in your garage. Think about where you want to make your modifications.
Review of the Best AR-15 Lower Parts Kits
Next, we’ll show you some of the best lower parts kits on the market. Even if none of these kits fit your barrel precisely, they should give you a good idea of what to look for in a lower parts kit for your individual carbine.
Bravo Company AR-15 Enhanced Lower Parts Kit
This kit is a bit on the pricier side, but it has a few upgrades to make it worth your while. It has an enhanced trigger guard and trigger assembly that are both designed to last longer and activate more readily. These are going to be more sensitive than a lot of the other trigger assemblies on the market, so if you’re planning to modify your carbine trigger, you might take a look at this kit.
It’s a military spec otherwise, so it comes with a predetermined array of parts that are built to military specifications. They’ll all be durable and long-lasting to some degree. The pistol handgrip is black and everything comes in a small bag without a carrying case, so you’ll need to package it yourself if you want to perform repairs somewhere other than your garage.
This kit comes with a pair of enhanced trigger parts that allow you to customize your carbine to a small extent. The rest of the kit is a standard military bag that can be relied upon for consistency and good lifespan.
Best for the Money:
CMMG AR-15 Lower Gunbuilder’s Lower Parts Kit
This is a great kit for money if you’re in this market primarily for repairs. You see, this kit lacks a trigger, grip, or trigger guard. This both lowers the overall weight for the kit and lowers the price, allowing you to get all of the other parts, such as pins or bolt catches, for an amazing price.
This is the top choice for repairs. You’ll be able to fix virtually anything wrong with your carbine’s lower half without having to shell out a lot of money for professional work. This does mean that this kit is strictly for repairs or if you’re making a carbine out of an amalgamation of other parts from previously-used AR-15s.
If you’re building an original gun, you will want to avoid this kit since it’s missing a few key components.
This kit is strictly for repair jobs or if you’re building an AR-15 with a trigger, trigger guard and grip already selected from a previous model since it lacks those pieces. However, that shortcoming allows you to get all the other pieces for your carbine lower at a phenomenal price.
Brownells AR-15 Receiver Set w/ Lower Parts Kit and Stock
This kit is practically the opposite of the previous kit we reviewed. It comes with a lower parts kit that’s made in the military spec, complete with every possible part you could need for repairs or builds. Everything is made to last and to high military quality.
More importantly, this kit comes with a Brownells exclusive upper receiver. This part is made in the U.S.A. and is chambered for NATO 5.56 rounds, one of the most common types used for AR-15s. Therefore, this kit is a great choice if you plan to use those types of rounds for your build anyway.
The kit also comes with a collapsible buttstock assembly to help finish your build. By purchasing this kit, you can progress your build by many milestones at once. However, if you only need a few parts to finish your current build or you just need repairs you should avoid this kit, especially since it’s all quite expensive.
This kit comes with a standard bag of mil-spec lower parts along with a collapsible buttstock and an upper receiver that’s chambered for NATO 5.56 rounds. If you’re building an AR-15 for those rounds already this is a great choice.
4. Palmetto State Armory Lower Build Kit
This kit is a military spec design, so it’s based on plans and outlines used by the U.S. military. This means that, opposed to a premium kit, you’ll find that using these pieces is easy and they all fit together very well. You shouldn’t have any trouble working each individual piece into its place.
On top of this, everything in the kit is made from the highest possible quality of their material. The springs are sturdy but springy, and the grip and other metallic pieces are thick but weighty in the right way. The kit as a whole isn't too heavy or bulky to carry around.
However, all of the parts in this kit are designed via the MOE standard. This refers to the Magpul Original Equipment and is great for standard AR-15 builds, but if you're looking to add a little personal flair to your weapon, you might be disappointed by how normal it all looks. You can always be sure that MOE pieces are going to last a long time and work for an AR build, so it's really a question of individuality or total reliability.
For most folks, however, dependability is going to win out. This is a great kit for standard repairs, too, so if you’re just looking for a kit for maintenance purposes or to save money in the long run, we definitely recommend checking this kit out. It’s got everything most people could need in a lower parts kit.
This is a great example of a standard MOE kit that can be relied upon for its sturdy parts and military spec. It’s not the most custom set out there but it’ll net you good repairs or a solid start for your rifle lower every time.
5. DPMS AR-15 Lower Parts Kit
This kit actually comes packaged somewhat interestingly. It comes in a heat-sealed bag that’s labeled for resale, meaning that if you want to stockpile parts or resell them to someone else you can absolutely do so. However, given how affordable the part kit already is, we recommend going for this kit if you need some parts on the cheaper side of things.
In terms of specs, the kit is made in the military style so you can expect all of the already-mentioned features that come along with that design. The handgrip is a standard black color, nothing too unique or interesting. There’s no carrying case, which is unfortunate if you wanted to take the parts with you or repair on the go.
It should be noted that these parts are specialized to fit into AR-15 weapons only, so we don’t recommend trying to cross-use parts or buy a kit for an AR-15 and decide to use one of the springs for your pistol. It’ll only cause damage or harm, so avoid attempting that at any cost.
This comes in a bag so you can resell it at a later date if you so choose. The kit is mil-spec and made of parts that are designed to last.
There you have it; the best lower parts kits available. With any of these kits, you'll be able to start that awesome rifle build you've had in mind. Remember to check your barrel option before you make your final purchase and don’t be afraid to look up some videos or read more of our guides for helpful tips and pointers.