The last step to completing your AR-15 build is the lower receiver parts kit – so the sooner you get one, the sooner you can get out and test out your new build. Sometimes, you just want to get the cheapest, most complete kit and be done – I’m guilty of that myself – but you have to balance the parts with the amount of money you spend on them if you want a truly remarkable AR-15 build. My top two choices (from experience) in this category are the Bravo Company AR-15 BCMGunfighter Enhanced Lower Parts Kit (best overall) and the CMMG AR-15 Gunbuilder’s Lower Parts Kit (Mil-Spec lower parts kit).
Even though the Bravo Company AR-15 BCMGunfighter Enhanced Lower Parts Kit comes with a polymer trigger guard, it is affordable and comes with everything needed to finish your build like a champ. My favorite part is that it passes Bravo Company’s rigorous quality control process – so it will likely exceed all of your expectations. With mil-spec compositions, you might find discomfort with the grip, and you are not spared this with the CMMG AR-15 Gunbuilder’s Lower Parts Kit – however, what you do get is a complete mil-spec kit that exceeds mil-spec standards for a decent price.
Best AR-15 Lower Parts Kit Comparison Table
No matter what choice you make from the selections below for your AR-15 lower parts kit, I can guarantee that you will find what you are looking for in this review (and maybe an extra for your next build)!
Building your own AR-15 from parts is super cool. You can get a sweet rifle at a really good price.
However, the lower parts kit is an area where people tend to just get the cheapest thing on the market.
Bravo Company AR-15 BCMGunfighter Enhanced Lower Parts Kit
Key Specs:
- Cartridge:
.223 Remington
- Fabric/Material:
Nickel, Teflon
- Additional Features:
Polished Nickel Teflon Trigger
Pros:
Includes a pistol grip and trigger.
Trigger guard provides better trigger access than standard mil-spec trigger guards.
Safety selector provides very positive engagement.
AR-15 lower parts kits matter more than you might think
An AR-15 lower parts kit is mostly just buttons, levers, springs, and pins. A lot of builders figure that as long as the parts are metal, they should be good to go.
However, this isn’t always the case.
Getting the best AR-15 lower parts kit for your rifle ensures that everything will fit well when you put it together and that none of the parts will cause you problems in the long-run.
When one of your pins backs out while you’re shooting or your safety selector breaks, you’ll wish you’d invested a little more time and money for the best lower receiver parts kit for your rifle.
Fortunately, all you need to do is get a lower parts kit from a good manufacturer. This saves you from any headaches, most of the time.
I work in a gunsmithing shop. I’ve seen a ton of lower parts kits and installed almost just as many.
Let’s talk about lower parts kits, just in case you’re not sure which manufacturers are the good ones.
SPOILER: if you’re dedicated to just getting the parts and being done with it, get the Bravo Company AR-15 BCMGunfighter Enhanced Lower Parts Kit. It’s probably the best value in any lower parts kit, dollar for dollar.
For those who are interested in browsing the other options, stick around and we’ll show you what’s out there.
Table of Contents
Are all AR-15 lower parts kits the same?
Yes and no. All AR-15 lower parts kits come with most of the parts you need to assemble a functional AR-15 lower receiver, and almost all lower parts kits will work in any AR-15 lower receiver. However, there are often differences in quality and design.
In terms of quality, the main thing to look for in an AR-15 lower parts kit is the fit and finish.
All the pieces in a lower parts kit are small parts. Poor fit and finish can make your lower receiver to function sluggishly or parts not to fit into the lower receiver.
When you get a lower parts kit, it’s a good idea to give it a quick check to make sure the external finish on the parts is smooth and evenly applied. Also check all the metal parts for burs.
When you’re installing your lower parts kit, do a quick fit check on each part before you install it.
Make sure that each part moves freely inside the lower receiver, if it needs to. If there’s any stiffness or binding, you may need to replace that piece or get a replacement lower parts kit.
Then, once your lower parts kit is installed, function check your lower receiver.
Make sure the trigger releases the hammer, that the safety stops the trigger from being pressed when the rifle is on SAFE, and that the magazine locks into place and releases easily.
What all comes in a lower parts kit for AR-15?
These are the parts that come in almost all lower parts kits for AR-15 rifles: magazine catch, magazine release, bolt catch, safety selector, pivot and takedown pin, and the springs and detents for installing these parts. Some lower parts kits come with additional components (i.e. trigger and pistol grip).
Still other lower parts kits also include the recoil mechanism components: buffer tube (also called a lower receiver extension), castle nut, end plate, buffer, and buffer spring.
What is an enhanced lower parts kit?
An enhanced AR-15 lower parts kit usually comes with an ambidextrous safety selector, bolt catch, and/or magazine release.
Some lower parts kits also come with a nickel boron finished trigger or trigger that’s upgraded in some other way.
Other enhanced lower parts kits may feature lightweight parts.
What spare parts should you have for an AR-15?
Having a spare lower parts kit on hand is a good idea. That way you have a replacement for every piece on your lower receiver.
However, if you just want to have a few small parts on hand, keep an extra bolt catch, magazine catch, and trigger springs.
The bolt catch is easier to break than most people realize.
If you dry fire the rifle without the upper receiver on, the hammer can break the bolt catch. Bolt catches can also break from normal use, even if you’re nice to your guns.
Mil-spec magazine catches use a steel rod press-fitted into another steel piece. Sometimes this press-fitting fails. Then your magazine catch literally falls apart.
Springs wear out with use, and trigger springs (hammer, trigger, and sear springs) get the most use. They tend to wear out the fastest and have the most potential for breakage.
If you have these three lower receiver parts on hand, you can deal with the most common broken part issues.
However, having a complete spare lower parts kit is still a good idea, just in case something uncommon goes wrong.
AR-15 lower parts kit reviews: Sweating the small stuff
Our winner gets the honors of the top spot, all the other lower receiver parts kits are reviewed after that.
Time to piece this together.
1. Bravo Company AR-15 BCMGunfighter Enhanced Lower Parts Kit
Pros:
- Includes a pistol grip and trigger.
- Trigger guard provides better trigger access than standard mil-spec trigger guards.
- Safety selector provides very positive engagement.
Cons:
- Trigger guard is polymer.
Bravo Company produces workhorse AR-15 rifles. They’re affordable, and they just run like champs.
The Bravo Company AR-15 BCMGunfighter Enhanced Lower Parts Kit is the lower parts kit that you’d get on almost any complete Bravo Company rifle.
The big bonus of this kit is that it includes a pistol grip and trigger. Even though you might not have a stock, this kit has all the parts you need to build a complete weapon, as far as the ATF is concerned.
And, the pistol grip and trigger aren’t flimsy freebie parts. They’re legitimate Bravo Company hardware. Given the price, that alone makes this kit a good value.
All the other parts are machined or forged to exceed mil-spec standards, and are subject to Bravo Company’s rigorous quality control process. So, you know your parts will fit your lower right out of the box.
The only thing that’s technically not mil-spec is the trigger guard. That’s because it’s better than mil-spec. It’s a curved trigger guard that gives you better access to your trigger.
The safety selector is also remarkably positive. It’s not so stiff that you have to work to flip it. But, the engagement is tight and crisp. So, you won’t accidentally engage or disengage your safety.
Since this is a mil-spec kit, there’s no ambidextrous controls. So, standard lower receivers only!
All in all, this kit is an excellent value for the money. You could easily drop this kit into your lower receiver and never buy replacement lower parts again.
2. Luth-AR AR-15 Lower Parts Kit
Pros:
- Super affordable.
- Parts usually require no fitment.
- Meets all the mil-spec requirements.
Cons:
- No included trigger guard.
- Safety selector is a tad mushy.
Often, these extremely affordable parts kits are considered only good enough for budget, “poverty pony” AR-15s. The Luth-AR AR-15 Lower Parts Kit might come at a poverty pony price.
It’s much better than poverty pony quality, though.
Obviously, the main selling point of this kit is the price. It doesn’t get much lower.
However, Luth-AR constructs their parts with an eye for fit.
So, even though this is a super affordable kit, the parts fit well without any fitment. In fact, some say that Luth-AR errs on the side of easier assembly, rather than tighter finish fit.
There are only two real complaints about this lower parts kit: the trigger guard and the safety selector.
First, there is no trigger guard. Most people put some sort of enhanced trigger guard on their rifles these days. But, it’s still a handy thing to have in the kit.
Second, the safety selector suffers from a tad bit of the mush that mil-spec safety selectors are known for. You won’t engage or disengage it accidentally.
However, when you flip the safety throw, it creeps a bit before it clicks over.
Some shooters don’t care about that. If you’re a die hard for a really crisp safety selector, this one might irritate you.
It might not be perfect. This kit is the way to go if you’re doing a budget build, and want to save a few bucks here and there without compromising function.
3. CMC Triggers AR-15 Lower Parts Kit
Pros:
- Incredible fit and finish.
- Polished safety selector and magazine release button.
- Includes enhanced aluminum trigger guard.
Cons:
- No trigger pins included.
The CMC Triggers AR-15 Lower Parts Kit is one of the highest quality kits you can get, and it’s impressively affordable.
It’s the fit and finish that really sets this kit apart.
The finish is excellent. It’s deep black and incredibly smooth.
The magazine release button and safety selector have also been polished for the smoothest possible movement, and it works.
The safety selector is super crisp, right out of the box—no break in needed—and the magazine release is flawless.
Additionally, all the other parts fit incredibly well. This is just a super well-made lower parts kit.
As a bonus, this kit also comes with an enhanced aluminum trigger guard. It’s a nice touch.Overall, if you want the best lower receiver parts you can get, for an excellent price, get this kit.
4. Geissele Automatics AR-15 Lower Parts Kit
Pros:
- Impressively affordable.
- Excellent quality for the money.
- Super positive safety selector throw.
Cons:
- May require some fitment to install.
Geissele Automatics is renowned for their AR-15 triggers and parts. Geissele has even won some military contracts recently.
The Geissele Automatics AR-15 Lower Parts Kit is hard to beat if you’re trying to keep costs as low as possible, while maximizing build quality.
Now, part of the reason the price is so good is because there’s no included AR-15 trigger or pistol grip. Remember to factor in those costs.
However, the parts are incredibly high quality in terms of machining and forging. The parts will last once you get them installed.
This kit also includes the Geissele Maritime Bolt Catch, which is one of the best bolt catches ever. You get quality and comfort from this lower parts kit.
Additionally, the safety selector has a nice positive throw that’s difficult to actuate unintentionally. Unfortunately, it’s not reversible like some mil-spec safety selectors.
It may take a little bit of work to get some of the pins installed, though. Geissele uses pins that are a tiny bit oversized to ensure they stay in place, no matter what.
Overall, this kit works nicely for its intended function: it’s a solid lower parts kit that works well and feels great.
5. CMMG AR-15 Gunbuilder’s Lower Parts Kit
Pros:
- Complete mil-spec kit, including pistol grip and trigger.
- Finish exceeds mil-spec standards.
- Safety selector is nice and crisp.
Cons:
- Mil-spec pistol grips are uncomfortable.
- The trigger is probably heavier than stated, because it’s a mil-spec trigger.
At my range, we’ve had some struggles with certain high-end AR-15s. Every time, we throw a CMMG bolt carrier and bolt in the gun, and it runs flawlessly. We also use CMMG lower parts kits to replace broken parts on our rental guns.
Based on the quality of their bolt carriers, the CMMG AR-15 Gunbuilder's Lower Parts Kit is a great deal, full stop.
There’s also a more complete CMMG AR-15 lower parts kit, which is a great option for anyone who wants both a mil-spec construction and mil-spec aesthetic. It comes with an A2 pistol grip, trigger guard, and trigger.
Now, this is both a benefit and a warning.
A2 pistol grips aren’t that comfortable, and the grip angle makes for awkward trigger finger placement.
The trigger guard makes it tough to access the trigger with gloves on.
The trigger itself is, well, mil-spec. CMMG states that the trigger press is 6 to 6.5 pounds. However, mil-spec triggers often pull heavier than specified.
All the parts fit really well. You’ll be able to put your lower together without sanding or filing.
Also, CMMG actually exceeded the mil-spec standards for the hard coat anodization. The finish is actually a bit thicker than ordinary mil-spec. But, it still looks the same.
Additionally, the safety selector is more positive than most mil-spec safety selectors. There’s no real creep or mush before the selector clicks into position.
So, if you want mil-spec hardware, this is a great option. It looks like mil-spec equipment. It’s just a tad better in terms of performance.
6. Aero Precision AR-15 Enhanced Lower Parts Kit
Pros:
- Includes everything but the buffer tube components—including fire control group and pistol grip.
- Phosphate finish on the steel components is excellent.
- Trigger guard is functional and comfortable.
Cons:
- Mil-spec trigger is nothing special.
Aero Precision is one of the best AR-15 component manufacturers out there, right now. They make quality hardware, and their prices are incredibly reasonable.
That’s what makes the Aero Precision AR-15 Enhanced Lower Parts Kit such a good AR-15 lower parts kit for the money.
It’s not the least expensive lower receiver parts kit you can get. It’s the most complete AR-15 lower parts kit for the money.It comes with most of the components you need to complete your lower receiver—minus the buffer tube components. Everything that goes inside the lower receiver is in this kit, including a trigger and a Magpul MOE pistol grip.
The steel components are finished in black phosphate, the standard mil-spec finish. However, the Aero Precision phosphate finish is nicely smooth and black, without the blotchy, gray appearance that phosphate finishes are known for.Additionally, the Aero Precision trigger guard is flared for easier access with gloves (and easier access in general). It’s also a nicely shaped trigger guard that doesn’t give you blisters on your middle finger when you shoot a lot.
Overall, the quality to price ratio is very high here. That’s what makes this such a great AR-15 lower parts kit for the money.
7. PSA MOE EPT Lower Build Kit
Pros:
- Comes with everything you need except the lower receiver itself.
- Trigger is finished in nickel boron for a smoother press and cleaner break.
- Phosphate finish is decently smooth and black.
Cons:
- Trigger has standard mil-spec pull weight—around 6lbs.
The PSA MOE EPT Lower Build Kit is special for a couple of reasons.
First, it comes with all the lower receiver components except the lower receiver. That includes the buffer tube components, Magpul MOE pistol grip, and a Magpul CTR stock.
If you have the lower receiver, this build kit has everything you need to make it shootable.
Additionally, this kit comes with an upgraded trigger. Yes, it’s a mil-spec trigger.
However, all the components are nickel boron coated to give you a smoother trigger press with a crisp break.
The trigger pull weight is still probably near 6 pounds. It’s better than a standard phosphate mil-spec trigger, though.
Everything else is standard mil-spec hardware, with a phosphate finish. It’s a pretty good phosphate finish.
It might not be as smooth as some other manufacturers’ phosphate finishes. It’s decently deep black and not too blotchy.All in all, the quality and completeness of this build kit are more than worth the price, which is totally fair, by the way.
The Final Shot
Your lower receiver parts kit is often the last stop on your way a completed rifle. So, the sooner you get one, the sooner you can sit down and finish your build that’s been waiting patiently to be finished.
Now if you are into customizing rifles, you may want to read our review on AR-15 9mm conversion kits just so you'll get an idea on more great modified builds.
Bravo Company AR-15 BCMGunfighter Enhanced Lower Parts Kit
Pros:
- Includes a pistol grip and trigger.
- Trigger guard provides better trigger access than standard mil-spec trigger guards.
- Safety selector provides very positive engagement.
Cons:
- Trigger guard is polymer.
Your lower receiver parts kit is often the last stop on your way to a completed rifle.
So, the sooner you get one, the sooner you can sit down and finish your build that’s been waiting patiently for a little TLC.
There are a lot of great lower parts kits out there. Don’t let a few buttons, latches, and springs keep you from finishing your build.
Get yourself a kit—the Bravo Company AR-15 BCMGunfighter Enhanced Lower Parts Kit and the CMMG AR-15 Lower Parts Kit are excellent and affordable options.
Then you can go shoot your new rifle, which is the fun part.
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