Best AR-15 Lower Parts Kit Review

Sharing is caring!

We all know that building your own AR-15 is a rite of passage for anyone immersing themself in the world of firearms. This gun is a tried and true staple in the firearms industry. If you plan on building one, then you’d need the best AR-15 lower parts kit. First introduced in the 1950s, the AR-15 has been the go-to assault rifle for both military and civilian use. Designed by Eugene Stoner, it is built to address the issues that plagued firearms used in World War II. It was made to easily be carried, operate in harsh environments, and most importantly be semi or fully automatic. It has since been adopted by the military as the M16 and M4A1 firearms. It is also a hugely popular civilian rifle since Americans reportedly own more than 15 million AR-15s, according to the National Rifle Association.

Best AR-15 Lower Parts Kit Review

This widespread popularity gave rise to a lot of DIY kits that can be used to repair and even build new AR-15 firearms using scrap parts. It also helps that the AR-15 is designed to be easily maintained and worked with. Some firearm enthusiasts even say that building an AR-15 is like building LEGO with its versatility and variety of parts. This sentiment is also shared with its cousin, the AR-10. However, the difference between the AR-10 vs AR-15 is that the AR-15 is chambered for .223 Remington or 5.56mm rounds. Meanwhile, the AR-10 is chambered for the 7.62mm rounds simi lar to the AK-47.

What Is a Lower Parts Kit?

An AR-15 consists of a hundred individual parts. Most of these parts are concentrated at the lower part of the receiver and are arguably the most important. This consists of the trigger group, safety, hammer, grip, magazine catch, and buffer assembly – to name a few. Of course, you can individually source all the needed parts to build your AR-15 lower but it can become tedious. So you can make this job a lot easier by getting some of the best AR-15 lower parts kits or finding the best LPK.

What Is Needed to Complete an AR-15 Lower Parts Kit?

All in all, about 30 parts are needed to complete an AR-15 lower kit. It is important to note though that not all LPK’s are the same. Some do not come with a buffer assembly and grip. Some would even come with a stock and some accessories. Now, when you want to build this amazing weapon, keep in mind the AR-15 lower parts list:

ar-15 list of lower parts
Image source:
  1. Hammer
  2. Hammer Spring
  3. Trigger
  4. Trigger Spring
  5. Hammer & Trigger Pivot Pins
  6. Disconnector
  7. Disconnector Spring
  8. Bolt Catch
  9. Bolt Catch Plunger
  10. Bolt Catch Spring
  11. Bolt Catch Roll Pin
  1. Pivot Pin
  2. Buffer Retainer
  3. Buffer Retainer Spring
  4. Magazine Catch Button
  5. Magazine Catch Spring
  6. Magazine Catch
  7. Take Down Pin
  8. Selector
  9. Selector Detent
  10. Selector Detent Spring
  11. Trigger Guard
  1. Trigger Guard Roll Pin
  2. Trigger Guard Screw
  3. Pistol Grip
  4. Grip Screw
  5. Grip Screw Washer
  6. Take Down/Pivot Pin Detent
  7. Take Down/Pivot Pin Detent Spring
  8. Buffer Tube/Receiver Extension (Not Shown)
  9. Buffer Spring (Not Shown)
  10. Buffer (Not Shown)
  11. Stock (Not Shown)


Top AR-15 Lower Parts Kit Available in the Market

Top AR-15 Lower Parts Kit Available in the Market

Browsing through your favorite online gun store might leave you with a headache. There are quite a lot of AR-15 LPKs to choose from anywhere you look. Right now, you’re probably wondering what kit to buy. Let’s take a look at some of the best AR-15 lower parts kits currently available in the market.

Palmetto State Armory Magpul MOE Lower Parts Kit

The PSA Magpul MOE lower parts kit is among the top-rated AR-15 LPKs in the market. Being a PSA product, this LPK is one of the best for the money. It features high-quality components from Magpul, which is arguably the best inexpensive brand out there. This kit is perfect for beginners as it features all things you would ever need to finish a lower. Some of them are even nickel coated to provide a smooth trigger action. To top it all off, this LPK even comes with a stock.


  • Magpul components
  • Complete set
  • Easy installation
  • Nickel coating
  • Comes with a stock


  • Mil-Spec trigger might be too heavy for some
  • Some parts are too small and do not fit tightly

Bravo Company Enhanced Lower Parts Kit

Bravo Company puts a huge emphasis on their products’ quality control. Their BCM enhanced lower parts kit is no different. It features a nickel Teflon finished grip with about 5.5 pounds of pull weight and a BCM MOD 3 grip. BCM knows that their products are used by civilians for self-defense use and they make kits that ensure that your AR-15 stays dependable no matter what. A downside of this kit however is the lack of an included buffer and stock assembly. While creating our AR-15 lower parts kit reviews, we’ve also learned that you can easily pair this with the BCM stock kit, which offers a fully complete and robust lower.


  • High-quality parts
  • Very durable
  • Close-fitting
  • Nickel-coated trigger


  • Does not include buffer assembly
  • A bit pricey if you want to go for a full lower

CMMG Lower Parts Kit

LPK’s from CMMG are by far the most popular out there. This is because CMMG kits are easy to install and are of decent quality at an affordable price. Another big plus is that the parts are put into color-coded baggies to help you find the parts easier and build the lower faster. It also includes extra springs and oversized takedown detents so that they are not easy to lose.


  • Easy installation
  • Color-coded baggies
  • Extra and convenient parts
  • A2 style hammer and grip


  • Does not include stock
  • Oversized bolt catch pin might be challenging to install

Geissele Automatics Lower Parts Kit

Geissele is a popular manufacturer of AR-15 parts and thus it is a no-brainer for them to enter the LPK market. If you’ve already selected a separate stock, grip, and buffer assembly then this LPK is the one you should get. It is a high-quality kit with precision-machined parts that can withstand a beating. With regards to price, considering that it lacks a grip and a stock, it is relatively inexpensive.


  • Compatible with most mil-spec lowers
  • High quality
  • Great value


  • Not a full kit

Brownells MOE Lower Parts Kit

Shop-brand kits have a reputation of not being of good quality but this LPK from Brownells is an exception. It is also a full kit with buffer and stock which is all the better. The stock and pistol grip are from Magpul while the buffer assembly is in-house. This is great for beginners and other AR-15 lower parts kit reviews agree. This kit is also reasonably priced. If you’re looking for a quick buy and you’re at Brownells, this is a good bet.


  • Comes with buffer and stock
  • Easy installation
  • Mil-Spec
  • Solid basic kit


  • Will be more expensive in the long run if you want to have all mil-spec parts

What Should You Look for in a Lower Parts Kit?

Building an AR-15 is a really interesting challenge. The AR-15 lower part kit is the most complex part of the rifle since it has the most moving parts. So to make this task a lot easier, you should only get the best LPK for your AR-15. And for that, you need to pay attention to:


What Should You Look for in a Lower Parts Kit

If you’re not starting from scratch and let’s say you already have a stock and pistol grip, then you don’t need to go for a full parts kit. Something like the LPK from Geissele will do. Conversely, if you are starting from scratch with just a bare AR lower, then go for a full kit. You can even mix and match parts from different LPKs as long as they are compatible.

Quality Manufacturing

You should always go for the best AR-15 lower kit that includes components from reputable brands. The lower is composed of tiny moving parts and if one fails, your gun may not even fire. Some of the components also have to be precisely machined and coated to ensure a smooth and reliable operation. Thus always make sure to choose manufacturers that advertise carrying out both magnetic particle and high-pressure testing on their components.

Corrosion Resistance

One of the design philosophies of the AR-15 platform is that it is supposed to handle extreme weather and environments. It should be able to get wet and have minimal damage. This is also important if you are living in humid areas. You have to ensure that all the important elements in your AR-15 parts kit are resistant to corrosion. And if you want a lifetime corrosion resistance, then choose the best lower parts kit made of chrome.

Ease of Assembly

This is a godsend for beginners who are just dipping their toes in the world of AR building. If you are an inexperienced builder, go for the AR-15 parts kit that is easy to assemble Plus, there are plenty of online guides to help you out along the way. Kits with color-coded bags like the one from CMMG can be pretty helpful in avoiding any confusion.


All and all, AR-15 lower parts kits are a great help if you want to build this weapon yourself. Compared to individually sourcing 30 or so parts yourself, having the LPK will make building your AR-15 lower a breeze. Moreover, by getting the best LPK, you save yourself all the hustle and bustle that will most certainly arise when you build this weapon. So, we sincerely hope that our little guide will help you find only the best AR-15 lower parts kit 2023. So keep these little tips in mind, good luck, and stay safe!