The Best AR-15 Lower Parts Kits for the Money
In this guide, we'll be covering the best AR-15 lower parts kits.
Though lower parts kits are often overlooked, there are actually significant differences between the various kits on the market today—and quality counts. You don't want something like a small detent or spring to be what takes down your rifle.
That's why we've chosen the highest quality kits, made by manufacturers with extreme dedication to detail and quality control.
Best AR-15 Lower Parts Kit
We'll cover more about what's needed to complete an AR-15 lower and why we chose these options below, but first, here's our list of the best AR-15 lower parts kit options:
- Bravo Company BCMGUNFIGHTER Enhanced Lower Parts Kit is our choice for the Best Lower Parts Kit (includes a pistol grip and trigger).
- Pair with the BCMGUNFIGHTER Stock Kit to have everything you need to complete your lower.
- Geissele Lower Parts Kit offers exceptionally high-quality lower parts but does not include a trigger, buffer assembly, pistol grip, or stock.
- Brownells MOE Lower Parts Kit (includes everything you need, all in one kit)
- CMMG offers the Best Budget Lower Parts Kit, with color-coded parts bags for easy installation (includes pistol grip and trigger).
Compare the Best Lower Parts Kits in the table below:
| Lower Parts Kit | Includes Trigger | Includes Pistol Grip | Includes Buffer Assembly | Includes Stock | Price |
|---|---|---|---|---|---|
| ✔ | ✔ | |||
| |||||
| ✔ | ✔ | ✔ | ✔ | |
| ✔ | ✔ |
Kits and Parts to Finish Your Lower
As you probably noticed in the table above, most lower parts kits don't include all of the parts you need to complete an AR-15 lower receiver. This is because many AR-15 builders like to choose their pistol grip, trigger, buffer assembly, and stock separately.
The Brownells MOE kit includes everything you need, but the BCM Stock Kit can be used to round out the BCM Enhanced and CMMG Kits.
| Stock Kit | Price |
|---|---|
| $113.99 |
Those who want to customize their lower further, may want to check these guides:
We'd also highly recommend the Radian Weapons Talon Ambidextrous Safety Selector for those who prefer ambi controls. I run this on nearly all of my AR builds.
| Safety Selector | Price |
|---|---|
| $52.20 |
What Parts are Needed for a Complete AR-15 Lower?
So you have a stripped AR-15 lower that you're needing to complete, what other parts should you get?
There's a pretty long list of AR-15 parts that are needed. For first time builders, it will seem overwhelming, but don't worry! Building an AR-15 lower is actually quite simple and requires few tools.
Full AR-15 Lower Parts List
Before you look at this picture of all the parts, let me say I can barely put together IKEA furniture but have managed to build numerous AR-15 lowers. Despite being the opposite of mechanically inclined, I usually manage to get it done in about 30 minutes.
Here's a full list of all the parts needed to complete an AR-15 Lower:
- Hammer
- Hammer Spring
- Trigger
- Trigger Spring
- Hammer & Trigger Pivot Pins
- Disconnector
- Disconnector Spring
- Bolt Catch
- Bolt Catch Plunger
- Bolt Catch Spring
- Bolt Catch Roll Pin
- Pivot Pin
- Buffer Retainer
- Buffer Retainer Spring
- Magazine Catch Button
- Magazine Catch Spring
- Magazine Catch
- Take Down Pin
- Selector
- Selector Detent
- Selector Detent Spring
- Trigger Guard
- Trigger Guard Roll Pin
- Trigger Guard Screw
- Pistol Grip
- Grip Screw
- Grip Screw Washer
- Take Down/Pivot Pin Detent
- Take Down/Pivot Pin Detent Spring
- Buffer Tube/Receiver Extension (Not Shown)
- Buffer Spring (Not Shown)
- Buffer (Not Shown)
- Stock (Not Shown)
The diagram above shows the BCM Enhanced Lower Parts Kit, which I highly recommend and many agree to be one of the best lower parts kits available. BCM makes exceptionally high-quality products and this kit offers the:
- BCM PNT Trigger (Single stage, polished, nickel Teflon finished, with 5.5 lb trigger pull).
- BCM MOD 3 Grip
- BCM Trigger Guard
$119.99 at Brownells
Prices accurate at time of publishing
This lower parts kit is missing a few parts, however:
- Buffer Tube/Receiver Extension
- Buffer Spring
- Buffer
- Stock
- Castle Nut
- End Plate
You can match the BCMGUNFIGHTER Lower Parts Kit with the BCMGUNFIGHTER Stock Kit that includes all of these parts.
$116.99 at Brownells
Prices accurate at time of publishing
Included is the BCMGUNFIGHTER Stock which is on our list of the best AR-15 stocks, due to its incredibly durable design, despite weighing just 7.5 oz.
What Separates Lower Parts Kits From One Another
The two major reasons to go with a reputable manufacturer are the quality of their products and the manufacturer's quality control.
Quality Control
Even when you're just buying a basic lower parts kit, not including triggers, pistol grips, or buffer assembly parts, there's still a benefit to paying a bit more for your kit.
Manufacturers like BCM and Geissele know their parts may very well be used in battle or in a civilian self-defense scenario. They pay special attention to ensuring everything is up to spec.
BCM Enhanced Lower Parts Kit
Product Name: BCM Enhanced Lower Parts Kit
Summary
The BCM Enhanced Kit is our choice for the best lower parts kit. Like all products made by Bravo Company, they put a huge emphasis on quality and quality control.
It also comes with one of our pistol grips (the BCMGUNFIGHTER MOD 3), plus it comes with an above average mil-spec trigger. You can pair it with BCM’s Stock Kit to have absolutely everything you need to complete your lower receiver build.
Geissele Lower Parts Kit
$47.99 at Brownells
Prices accurate at time of publishing
You can also be a lot more confident that everything will arrive and no parts will be missing. I've personally had missing parts when buying lower parts kits from cheaper manufacturers, and I'd rather pay a few bucks more than have to deal with contacting the retailer or manufacturer.
Quality
Difference between parts really comes into play when you buy a kit that includes a trigger, pistol grip, or buffer assembly.
I've purchased the below CMMG lower parts kit in the past that is cheaper than the BCM one I recommend.
CMMG Lower Parts Kit
$69.95 at Brownells
Prices accurate at time of publishing
What I did NOT do, was use the pistol grip or trigger that came with it. The trigger would likely be serviceable, though I don't think it's as nice as the BCM PNT or ALG Defense Combat Trigger. The pistol grip, on the other hand, feels incredibly cheap, flimsy, and uncomfortable.
If your budget is super tight, you could use this kit, but I'll bet you'll want to be upgrading the trigger and pistol grip ASAP.
I will say that the two times I've bought this kit, everything showed up, and I've had no issues with the parts of it I've actually used. It's also nice to have an extra trigger/hammer and pistol grip lying around—just in case.
The Best Lower Parts Kit for Beginners
If you just want to buy one kit that comes with everything you need, then the Brownells MOE kit is likely the best lower parts kit for you.
It includes an ALG Defense Combat Trigger (single stage, nickel-Teflon plated, 6 lb trigger pull), Magpul MOE stock, and Magpul MOE pistol grip. It also includes a Brownells buffer tube assembly with a carbine buffer.
Brownells MOE Lower Parts Kit
$221.99 at Brownells
Prices accurate at time of publishing
While I personally prefer the BCM lower parts kit and stock kit, this is another great option.
