27 Best Parts For Ar-15 Build – How To Build AR-15? 2024 Guide

We’ve seen a lot of interest from people who want to know how to build an Ar-15 and what the best parts for an AR-15 build are.

So we created a complete list of everything you need to build an AR-15 rifle! Our recommendations are based on what experts have used in the past on their own AR-15 builds.

After saying that, there are so many different ways to build an Ar-15 and there are also really good AR-15 build kits that you can buy. In the end, do your research and figure out what you want based on your budget.

And each Ar-15 build is going to be different, depending on your reasons for building a rifle. Hopefully, this guide will narrow this down for you and lead you in the right direction!

Let’s get started!

Does building your own AR-15 have its benefits?

AR-15 (gun review)

Yes, there are lots of benefits to building your own AR-15 over buying a completed factory AR-15. Some benefits include:

  • Cost – It can cost a lot less to build your own Ar-15 rifle when comparing part for part.
  • Knowledge – You know every single thing that your gun is made out of and understand how it functions.
  • Pride – You built it yourself, pretty awesome.
  • Satisfaction – Every part is exactly what you wanted.

How long will it take?

Once you have all of the parts and some step-by-step instructions, you could build your AR-15 in just 3 hours.

We highly recommend that you find some quality step-by-step instructions. Follow some people on YouTube, or get some instructions from a manufacturer. There is tons of information out there about how to build an AR-15.

The only problem is that you’ll spend lots of time trying to figure out what is good or bad practice, especially if you’re new at building a custom AR-15.

Sure, you can find free info, but it will take some time to figure out who is telling you how to build the AR-15 correctly or not.

Our Recommendation To Build Your AR-15 Correctly

Our recommendation is to buy this instructional DVD.

It spends a lot of time teaching How and Why to Build an AR-15 correctly.

It’s a very well-made video and you’ll have your AR-15 built within 3 hours.

Design Your Dream AR-15

If you are a visual person and would like to see what all of the different parts would look like when assembled together, you can design it.

With the design-builder you can:

  1. Build a NEW gun from scratch using the drop-down menus
  2. Build a replica of an existing AR-15 and see how upgrades will look
  3. Select a premade gun from a list of complete receivers
  4. Browse guns you’ve created and saved to update or compare.

AR-15 Parts List – 2024

AR 15 Beginners Guide (What parts do you need to build a rifle.)

Ok, now onto our AR-15 build parts list.

There are so many places where you can go to buy your own Ar-15 parts.

We choose Brownells.com. They have access to all of the best parts for an AR-15 build.

They also have over 90,000 other gun parts, tools, and supplies so it’s easy to find exactly what we need and all in one place.

1. Lower Receiver

To start, you need a lower receiver. You can get either a stripped lower receiver or an 80% lower receiver. We’ve tried to narrow down the best lower receivers by category below:

Stripped Lower Reciever

The stripped lower receiver is the lower receiver with a serial number on it completed by the manufacturer. It’s basically what makes your AR-15 a gun and legal.

The AR-15 stripped lower receivers must ship to a Federal Firearms License (FFL) dealer and you have to pass a background check before you can actually have it.

Best Stripped Lower Receiver Parts:

80% Lower Reciever

An 80% lower receiver is approximately 80% finished in the overall milling process.

80% lower receivers do not require a copy of a FFL to purchase, but do require the purchaser to “drill and mill” the lower in order to install the trigger control group.

Best 80% Lower Receiver Parts:

2. Lower Parts Kit

Polymer 80 Lower Reciever Kit

In order to assemble the AR-15 lower receiver, you’re going to need all of the parts to assemble it. 31 parts to be exact.

These parts include the trigger, bolt catch, springs, pivot and takedown down pins, selector switch and hammer.

The most convenient way to get all of these parts is by purchasing an AR-15 lower parts kit.

Most of these kits have all 31 parts necessary, and also include a pistol grip and trigger.

Some of the parts in the kit you may want to get rid and purchase higher quality parts, like the pistol grip and the trigger.

Best Lower Parts Kits:

3. Ar-15 Pistol Grip

Upgrading to a more comfortable pistol grip for your AR-15 can make you more of an accurate shooter.

Pistol grips are meant to aid the shooter to steady the rifle for more control.

A basic pistol grip is included in the best lower parts kits, but we recommend upgrading to something comfortable and made a little better.

Best Ar-15 Pistol Grips​:

4. Trigger (Fire Control Group)

The fire control group (basically the trigger) is the part on an AR-15 responsible for the motion of the trigger.

It stops the trigger pull if the safety is on and aids in the eventual release of the hammer or striker.

The fire control group consists of:

  • Hammer and hammer spring
  • Trigger and trigger spring
  • Disconnector and disconnector spring
  • Two fire control pins

We recommend replacing the trigger group included in the lower parts kit with a better one. You can usually find much higher-quality trigger groups outside of a lower parts kit.

Best Ar-15 Triggers:

5. Selector

Battle Arms Development ambidextrous AR-15 selector

The selector is the safety switch on the Ar-15.

It’s also included in the best AR-15 lower parts kits, but in case you want a different selector, like one that is ambidextrous or left-handed, you have to get it separately.

Best Ar-15 Selectors:

6. Bolt Catch

When the Ar-15 magazine is empty, the bolt catch is meant to stop the bolt from traveling forward.

​These are also normally included in lower parts kits. But if you want a different style, consider buying it separately.

Best AR-15 Bolt Catch:

7. Magazine Release

This part is exactly as it sounds. It’s meant to release the magazine from the AR-15

The magazine release can also be found in an AR-15 lower parts kit.

​If you want to get a better AR-15 magazine release, consider buying one separately.

Best AR-15 Magazine Releases:

8. Bolt Carrier Group

The Best Bolt Carrier Group for Your AR-15

The bolt carrier group is what holes the bolt and moves the bolt. It resets the hammer as well.

It bolt carrier group includes:

  • Bolt carrier
  • Complete bolt
  • Firing pin
  • Carrier pin
  • Gas key

When the AR-15 is fired, the bolt carrier group holds most of the gas pressure. Without this, your AR-15 wouldn’t function.

The bolt carrier group is usually an overlooked piece, but an essential part to your AR-15 build.

Best AR-15 Bolt Carrier Groups:

9. Buffer​

The buffer is what slows the bolt down on the AR-15. It also reduces the recoil and wears on the AR-15.

They come in two different sizes:

  • Rifle
  • Carbine

They also come in four different weights from the lightest to the heaviest.

For an AR-15 chambered in .223 / 5.56mm, use the heaviest buffer (called an H3 buffer). This will allow your AR-15 to consistently lock the rifle’s bolt back.

Really the size of your buffer will be determined by the size of your stock.

For an A1/A2 stock, get a rifle buffer.

For a collapsible or adjustable stock, get a carbine buffer.

If you are building the AR in 9mm, buy a specific 9mm buffer assembly.

10. Buffer Tube

The buffer tube holds the buffer.

Buffer tubes come​ in three sizes and you need to choose the right tube for your stock:

  • Rifle
  • MIL-SPEC carbine
  • Commercial carbine

Best AR-15 Buffer Tubes:

11. Buffer Spring

AR Buffer Springs

The buffer spring is what brings the bolt of the rifle forward. Buffer springs allow your rifle to fire follow-up shots.

Best AR-15 Buffer Springs​

12. Barrel

One of the biggest differences in a cheap AR-15 vs a high0end AR-15 is the quality of its barrel.​

There are so many different types of barrels to choose from all dependent on a user’s preference.

Most AR-15 barrels fall into one of two categories:

  • made of chrome molly steel with a chrome-lined bore and chamber,
  • made of stainless steel, which typically does not have chrome lining in the bore or chamber.

The type of barrel you get will have an effect on your AR-15 performance.

Typically, chrome-lined barrels handle extensive shooting and adverse weather much better.

Stainless steel barrels are more accurate making it perfect for long-range target shooters.

Best AR-15 Barrels

13. Barrel nut​

The barrel nut is what holds the barrel to the receiver.

Best AR-15 Barrel Nuts​

14. Gas Block

The gas block directs the gases from the barrel to the gas tube and then back into the AR-15’s receiver.

This allows it to complete the cycling process so another round will fire.

Best AR-15 Gas Blocks​

15. Upper Receiver

The upper receiver consists of:

  • the forward assist
  • spring and pin
  • the ejection port cover
  • the charging handle
  • barrel
  • and bolt carrier group.

There are a few different ways to get your upper receiver.

One way is that you can purchase a complete upper receiver assembly that includes the barrel.

Or you can even buy an upper receiver that has no barrel, but includes the ejection port cover and forward assists.

Or you can buy a stripped upper receiver that is just the metal housing for all the parts.

Best AR-15 Upper Receivers:​

16. Upper Receiver Parts Kit

AR-15 Upper Receiver

The upper receiver parts kit includes:

  • ejection port door
  • spring
  • forward assist parts
  • sometimes the charging handle
  • It typically does not include the bolt or carrier

Best AR-15 Upper Receiver Parts Kits​

17. Charging Handle

The charging handle moves the bolt carrier that is inside the upper receiver.

What the charge handles does is it pulls the bolt carrier back. It also can aid in clearing a malfunction.

Best AR-15 Charge Handles

18. Gas Tube

Gas tubes vary in length, coming in rifle, mid-length, carbine and pistol lengths.

The gases are directed from the gas block to the bolt carrier via the gas tube.

Best AR-15 Gas Tubes​

19. Stock

There are a couple of different stock styles that you can buy:

  • Adjustable
  • or fixed

Depending on where you live, an adjustable or collapsible stock is illegal.

The AR-15 stock goes on the back of the rifle, allowing you to shoulder it.

Best AR-15 Stocks​

20. Handguards


The handguards go around the barrel of the AR-15.

Handguards are also referred to as the forend, foregrip or forearm.

The purpose is that they are meant to protect your hands from burning on a hot barrel.

Handguards come in different sizes:

  • rifle
  • mid-length
  • and carbine and pistol length

When picking out the parts for your rifle, the gas tube will also come in rifle, mid-length, carbine or pistol lengths.

Make sure you buy the same size handguard as the gas tube.

There are free float and standard handguards.

Standard handguards will touch the rifle’s barrel, while free-floating handguards will not.

Handguards serve a valid function, however, many people buy them purely on their aesthetic value

Best AR-15 Handguards

21. Delta Ring Assembly

The delta ring assembly includes:

  • the delta ring
  • weld spring
  • and snap ring.

If you choose to get a free float handguard, you will not need a delta ring assembly.

Best AR-15 Delta Ring Assembly

22. Front Sights

Since upper receivers come in two different types, A2 or A3 (flat top), you’ll need to get different types of sights based on the type of upper receiver you get.

Its fixed carry handle with integrated iron sights characterizes the A2 upper receiver.

The A3 flat top upper has no carry handle, but does have a Picatinny rail installed.

The A3 flat top upper allows you to add sights and optics, while the A2 (carry handle upper) does not.

Best AR-15 Front Sights

23. Handguard Cap​

The handguard cap secures the front of standard handguards. You don’t need one for free-float handguards.

Best AR-15 Handguard Cap

24. Muzzle Device

The Best AR-15 Muzzle Devices

There are two types of muzzle devices:

  • muzzle brake (sometimes called a compensator)
  • or flash suppressor/flash hider

The muzzle brake helps reduce recoil and muzzle rise.

The flash hider suppresses the visible flash from the barrel when the rifle is fired.

Some states restrict flash suppressors, but may allow muzzle brakes.

Best AR-15 Muzzle Devices

25. Magazines

AR-15 magazine capacity ranges from 5 to 100 rounds.

Some states restrict magazine capacity.

Best AR-15 Magazines

26. Optics

There are a lot of different types of AR-15 optics that you can get for you AR-15. Styles include:

  • variable optics with magnification
  • Fixed optics
  • red dot sights
  • holographic sights, like EOTech scopes
  • and non-electronic illuminated sights that offer no magnification.

27. Extras

There’s a lot of other things you can get for your AR-15. Some of these ‘extras’ include things like:

  • Sling mounts and attachments​
  • tools to make the build easier
  • etc.

You can visit any gun store or online gun website like Brownells to see what they have to offer with any AR-15 extras.

Final Thoughts – How to Build an AR-15 – Best Parts For AR-15 Build

Building an AR-15 can seem overwhelming at first. But​ knowing the right parts to get and a good guide to help you through the build process can make it much easier!

Hopefully, our recommendations will help you to fin

Good luck! Stay safe and happy shooting!​