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?
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 at Brownell’s ar15builder.com
With the design builder you can:
- Build a NEW gun from scratch using the drop down menus
- Build a replica of an existing AR-15 and see how upgrades will look
- Select a premade gun from a list of complete receivers
- Browse guns you’ve created and saved to update or compare.
AR-15 Parts List – 2021
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 an Federal Firearms License (FFL) dealer and you have to pass a background check before you can actually have it.
Best Stripped Lower Receiver Parts:
- Anderson Manufacturing MIL-SPEC stripped lower (shown)
- Aero Precision stripped lower
- Battle Arms Development forged stripped lower
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
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:
- Polymer80 AR-15 Lower Parts Kit
- Double Star AR-15 Lower Parts Kit
- CMMG AR-15 Lower Parts Kit
- Bushmaster Firearms AR-15 Lower Parts Kit (shown)
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 for comfortable and made a little better.
Best Ar-15 Pistol Grips:
- Hogue AR-15 Pistol Grip
- Magpul MOE AR-15 Pistol Grip (shown)
- Magpul MIAD AR-15 Pistol Grip
- A.R.M.S. throw lever quick detach AR-15 Pistol Grip
- Stark AR-15 Pistol Grip
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:
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:
- Battle Arms Development ambidextrous AR-15 selector (shown)
- Noveske Rifleworks AR-15 short throw selector
- Rock River Arms Round Profile Ar-15 Selector
- JP Enterprises AR-15 ambi safety selector
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 a lower parts kits. But if you want a different style, consider buying it separately.
Best AR-15 Bolt Catch:
- Brownells AR-15 bolt catch
- Badger Ordnance AR-15 bolt catch
- Seekins Precision Enhance AR-15 bolt catch (shown)
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:
- Seekins AR-15 magazine release button
- Troy Industries AR-15 ambi magazine release (shown)
- Norgon ambi AR-15 magazine release
- V Seven Weapon Systems AR-15 magazine release
8. Bolt Carrier Group
The bolt carrier group is what hols 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:
- High Standard AR-15 Bolt Carrier Group
- DPMS AR-15 Stripped Bolt Carrier Group (shown)
- Double Star AR-15 Bolt Carrier Group
- WMD Guns AR-15 Bolt Carrier Group
The buffer is what slows the bolt down on the AR-15. It also reduces the recoil and wear on the AR-15.
They come in two different sizes:
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.
Best AR-15 Buffers:
- Spikes Tactical AR-15 Heavy Buffer
- Spikes Tactical AR-15 Standard Buffer (shown)
- Crosshair AR-15 Carbine Buffer
- Rock River Arms AR-15 Carbine Buffer
10. Buffer Tube
The buffer tube holds the buffer.
Buffer tubes come in three sizes and you need to chose the right tube for your stock:
- MIL-SPEC carbine
- Commercial carbine
Best AR-15 Buffer Tubes:
- Colt AR-15 Buffer Tube Assembly
- DPMS MIL-SPEC AR-15 buffer tube assembly
- High Standard Ar-15 Commercial buffer tube assembly (shown)
11. Buffer Spring
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
- JP Enterprises AR-15 buffer spring
- Brownells 3-pack AR-15 buffer springs
- High Standard AR-15 buffer spring
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
- Brownells 16″ AR-15 Gas System Barrel
- Proof Research 12.5″ AR-15 Carbon Fiber Barrel
- Double Star 16″ AR-15 barrel
- White Oak Armament 16″ AR-15 Wylde match barrel (shown)
13. Barrel nut
The barrel nut is what holds the barrel to the receiver.
Best AR-15 Barrel Nuts
- DPMS AR-15 Barrel Nut
- Yankee Hill Machine Co. AR-15 Barrel Nut (shown)
- High Standard AR-15 Barrel Nut
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
- Yankee Hill Machine Co. AR-15 Gas Block
- Midwest Industries AR-15 Gas Block (shown)
- VLTOR Weapon System AR-15 Gas Block
15. Upper Receiver
The upper receiver consists of:
- the forward assist
- spring and pin
- the ejection port cover
- the charging handle
- 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 assist.
Or you can buy a stripped upper receiver that is just the metal housing for all the parts.
Best AR-15 Upper Receivers:
- Brownells AR-15 Complete Upper Receiver (shown)
- Aero Precision AR-15 Stripped upper receiver
- Radical Firearms AR-15 upper receiver assembly
16. Upper Receiver Parts Kit
The upper receiver parts kit includes:
- ejection port door
- forward assist parts
- sometimes the charging handle
- It typically does not include the bolt or carrier
Best AR-15 Upper Receiver Parts Kits
- DPMS AR-15 Upper Receiver Parts Kit for non-free float upper
- Aero Precision AR-15 upper receiver parts kit (shown)
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
There are a couple of different stock styles that you can buy:
- 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
- Magpul AR-15 Collapsible Stock (shown)
- Magpul AR-15 Collapsible stock MIL-SPEC
- Command Arms ACC AR-15 Collapsible stock commercial
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:
- 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
- Yankee Hill Machine Co. Diamond Pattern AR-15 Handguard (shown)
- Double Star AR-15 free float handguard
- DPMS AR-15 free float handguard
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
- Yankee Hill Machine Co. AR-15 Gas Block Front Sight
- Magpul AR-15 MBUS Sight
- Troy Industries AR-15 Battle Sights (shown)
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
- DPMS Round AR-15 Handguard Cap (shown)
24. Muzzle Device
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
- DPMS AR-15 compensator 22 caliber
- Smith Enterprise AR-15 Flash Eliminator
- Battle Comp Enterprises AR-15 compensator (shown)
AR-15 magazine capacity ranges from 5 to 100 rounds.
Some states restrict magazine capacity.
Best AR-15 Magazines
- Surefire 60 round AR-15 magazine (shown)
- Magpul 30 round AR-15 magazine
- Brownells 30 round AR-15 magazine
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.
Check out the best optics below for your AR-15:
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
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!