AR-15 Parts List For Building Your Own Rifle [Plus Our Favorite Parts]

After buying my first complete AR-15, I immediately wanted to try my hand at building one myself. The process ended up being a lot easier and more rewarding than I expected.

If you're looking to build your first AR-15 or just need a refresher, we've got you covered. Below you can find a full AR-15 parts list, including parts that we recommend and use ourselves.

AR-15 Build List

We'll go into more detail below, but here's a quick AR-15 parts list:

  • Upper Receiver Parts
    • Stripped Upper Receiver
    • Barrel
    • Muzzle Device (Flash Hider, Muzzle Brake, etc.)
    • Gas Tube
    • Gas Block
    • Handguard
    • Charging Handle
    • Bolt Carrier Group
    • Forward Assist
    • Dust Cover

AR-15 Upper Receiver Diagram and Parts List

A look under the handguard.

AR-15 Upper Gas System Parts

  • Lower Receiver Parts
    • Stripped Lower Receiver
    • Pistol Grip
    • Lower Parts Kit (Includes Trigger/Hammer parts, Safety Selector, Bolt Release, Magazine Release, etc.)
    • Optional Upgraded Trigger (from what comes with lower parts kit)
    • Buffer System (Buffer Tube, Buffer, Buffer Spring)
    • Stock or Pistol Brace

AR-15 Lower Parts Diagram and Parts List

Let's start off with all the parts that you need to complete your lower receiver. For each part, we've also linked comprehensive guides explaining what to look for and our full list of recommendations for each part.

Stripped Lower Receiver

In most states, the stripped lower receiver is the only part of an AR-15 where your purchase needs to be handled by a Federal Firearms Licensee (FFL). This is because it is the portion of the AR-15 that is serialized (technically the "firearm"). All other parts can usually be shipped directly to your door.

I generally just go with whatever is cheapest, so long as its a forged 7075 (T6) aluminum receiver. I've never had any issue with a cheap receiver and wouldn't bother spending up unless you're trying to build an ultra-lightweight rifle or want to go with something particularly unique.

Anderson (from $54.99) and Palmetto State Armory (from $49.99) are the regular manufactures I use.

Palmetto State Armory Stripped Lower

Aero Precision is another great option that's relatively affordable, though a bit more expensive than the previously listed options.

To learn more about choosing a lower receiver and see all of our favorite picks, check out our guide on the best stripped lower receivers.

Lower Parts Kit

Lower parts kits include all the springs, pins, and detents you need to build your lower receiver.

Choosing a lower parts kit can be a bit confusing because some include more parts than others.

Lower Parts KitIncludes TriggerIncludes Pistol GripIncludes Buffer AssemblyIncludes StockPrice
BCM Enhanced Lower Parts Kit

BCM Enhanced Lower Kit

$119.95

Geissele AR-15 Lower Parts Kit

Geissele Lower Parts Kit 

$49.00

Brownells MOE Lower Parts Kit

Brownells MOE Lower Parts Kit

$221.99

CMMG Lower Parts Kit

CMMG Lower Parts Kit

$73.99

For example, this Brownells MOE Kit includes absolutely everything you need to complete your lower receiver, including a pistol grip, stock, and buffer assembly.

Personally, I prefer BCM's parts kit over the one above because it comes with a better pistol grip and slightly better trigger in my opinion. With that said, I eventually end up swapping out the trigger anyway.

BCM Enhanced Lower Parts Kit

Unlike the Brownells kit, however, BCM's does not come with a buffer assembly or stock. The good news is BCM also offers the BCMGUNFIGHTER Stock Kit, which has all of the remaining parts you need to complete your lower.

BCMGUNFIGHTER Stock Kit

If you want to choose specific parts for things like the pistol grip, stock, buffer assembly, and trigger then you may want to go with a more basic lower parts kit. For that, we'd recommend the Geissele Kit or CMMG Kit.

Trigger

Some of the above lower parts kits include good Mil-Spec triggers, but they're still Mil-Spec triggers. Chances are you'll want to upgrade.

AR-15 Pistol Build w/ Geissele SD-E Trigger

 

My favorite triggers are Geissele's Super Dynamic Trigger Series. I have the Super Dynamic Enhanced Trigger (SD-E) in my favorite AR-15, shown above. The double stage trigger has a 2.3 lb first stage and a 1.2 lb second stage.

Geissele SD-E Trigger

A more affordable option that I love is Hiperfire's EDT series of triggers. the EDT Designated Marksman came with a complete AR-15 I bought and I liked it so much I bought another for a recent build.

The trigger is single stage and comes with two spring weights 4.5 or 5.5 lbs.

Hiperfire EDT Triggers

Pistol Grip

I wouldn't overthink the pistol grip too much. If you buy either the BCM or Brownells lower parts kits above, you should be fine with the grips that come with them. If you chose a more basic kit, check out our list of the best AR-15 pistol grips.

BCMGUNFIGHTER MOD 3 Pistol Grip

Buffer Assembly

The buffer assembly includes the buffer tube, buffer spring, and buffer weight. This plays a big role in how your AR-15 cycles and the recoil you'll feel. These parts are included in the Brownells kit above and the BCM stock kit.

The one note I will make is that you may want to experiment with different buffer weights. Most kits come with a carbine buffer, but you may want to try out a heavier H1, H2, or H3 buffers if you feel your rifle has too much recoil or is cycling "violently".

Stock or Pistol Brace

Along with a trigger, stocks are an AR-15 part that people frequently put some thought into.

Again, the stocks in the BCM and Brownells Kit above are perfectly fine for most people.

My personal favorite stock, however, is the MFT Minimalist. It's super lightweight at 5.8 oz and has a very wide buttpad.

Mission First Battlelink Minimalist

Those of you building a rifle specifically for long range precision shooting instead may want to check out this LUTH-AR ($131.55) stock or Magpul's PRS ($242.20).

You can compare more options in our guide to the best AR-15 stocks.

If you're building an AR pistol, the SBA3 pistol brace is the clear frontrunner in my opinion.

SBA3 AR Pistol Brace

If you don't want to take my word for it, you can find more options in the best pistol braces.

Making Your Complete Lower Your Own

Before moving onto our upper receiver AR-15 parts list, here's a small part you may want to consider to take your rifle to the next level of awesome.

Radian Talon

The Radian Talon ambidextrous safety selector is a must for me these days. It's the best ambi safety I've found and is easy to install. Personally, I find it really beneficial to have the option to adjust my selector with my index finger in addition to my thumb.

Radian Talon Ambi Safety

I haven't found the need, but you may also want to look into extended mag releases or oversized bolt releases.

AR-15 Upper Receiver Build List

Now let's move onto the parts you need to build your AR-15 upper.

Upper Receiver

Just like the lower receiver, my main focus in choosing a stripper upper receiver is that its forged 7075 (T6) aluminum.

I'd also recommend opting for an "assembled receiver" which already has the forward assist and dust cover installed unless you want to customize those. You can also choose upper receivers without a forward assist.

Check out our picks for the best upper receivers.

Barrel

The barrel of your AR-15 is definitely one of the most important parts to consider. It will play the biggest role in determining the accuracy of your rifle.

Stainless steel barrels are generally more accurate, but treated steel barrels tend to last longer.

This discussion is honestly too much to get into in this article, so be sure to check out our guide to the best AR-15 barrel. You'll also want to check out our guide to the best AR-15 muzzle devices.

Be sure whether or not your barrel comes with a gas tube and gas block. If not you'll have to buy those separately. Regardless, you may want to consider purchasing an adjustable gas block. Adjustable gas blocks allow you to tune your rifle to minimize recoil. We'd recommend this one by Superlative Arms.Superlative Arms Adjustable Gas Block

 

Bolt Carrier Group

Again, we have a very important part to consider - the bolt carrier group (BCG).

The BCG of your AR-15 is incredibly important because it plays the biggest role in the function of your rifle. It's also one of the parts most susceptible to wear and damage over time.

For rifles I need to be sure will go bang when I need them to, I always opt for a Bravo Company BCG. They're very well machined and exceptionally high quality. I've shot thousands of rounds with these BCGs without any abnormalities.

Best Bolt Carrier Groups

While I'd always choose the above BCG for a self-defense rifle, competitive shooters may want to opt for something more lightweight. Aside from the obvious benefits of not carrying around as much weight, this can also greatly reduce recoil.

Check out our list of the best AR-15 bolt carrier groups (BCG) for a look at our favorite lightweight options.

Charging Handle

The charging handle is what is used to pull back your bolt carrier group and chamber a round.

Despite trying out numerous options, I don't own an AR-15 without a Radian Raptor-LT charging handle.

Radian Raptor LT on Custom AR Pistol

You can look through all the best AR-15 charging handle options, but I'll also point out Strike Industries' ARCH-EL is a great budget-friendly choice.

Strike Industries ARCH-EL (red)

Handguard

If building an AR-15, I strongly recommend going with a free float handguard rather than a drop in handguard. It looks better, will make your rifle more accurate, and it will typically give you more mounting options.

There are three handguards I really like depending on what you're going for with your build.

For serious duty builds or SHTF rifle builds, I'd recommend the BCMGUNFIGHTER MCMR (M-LOK) handguard. It's what I have on my do everything AR pistol shown above.

BCM MCMR

Aero Precision's Atlas S-ONE M-LOK handguards are also awesome, but they only have mounting slots at the 3, 6, 9, and 12 o'clock positions. The tradeoff is they're lighter and more comfortable to grip.

Aero Precision ATLAS S-ONE M-LOK Handguard FDE

If you're going for a lightweight build, I love Faxon's carbon fiber handguards.

 

 

 

Faxon Streamline Carbon Fiber Handguard for AR15

For more options and to learn more about choosing a handguard, check out the best AR-15 handguards.

Optics and or Sights

The last essential parts you'll need are iron sights, a scope, and/or a red dot sight. I generally use a red dot sight, as well as back up sights for home defense rifles, though I only run a red dot on rifles I just shoot for fun. If you're building a rifle for long-distance shooting, you'll instead likely want to go with a scope.

Unless you're planning to only run irons, I usually just opt for the relatively affordable Magpul MBUS Sights.

Magpul MBUS Sights

As for red dot sights, if you can afford it, the Trijicon MRO is my favorite option. You can read our Trijicon MRO review or check out all of the best red dot sights. We also have a guide specifically on the best red dot sights under $200.

Trijicon MRO Red Dot Sight

Trijicon MRO
Trijicon MRO

Product Name: Trijicon MRO

Product Description: The Miniature Rifle Optic (MRO) is a 2 MOA red dot sight made by legendary optics manufacturer Trijicon. Its housing is made from 7075-T6 aluminum and it has up to 50,000 hours of battery life.

  • Sight Picture
    (5)
  • Usability
    (5)
  • Durability
    (5)
  • Reliability
    (5)
  • Battery Life
    (5)
  • Value
    (5)
5

Summary

The Trijicon MRO is our clear front runner for best red dot sight for AR-15s and other long guns. It’s made from a stronger material than most and is incredibly durable, yet has a superior sight picture to most other options. When you factor in the MROs 50,000 hour battery life, you can be confident this sight will be ready when you need it most.

Pros

  • Up to 50,000 hours of battery life
  • Waterproof to 100 feet and can function from -60°F to +160°F
  • Huge 25mm objective lens, offering a great sight picture
  • More affordable than other top optics

Cons

Legal Disclaimer

You are entirely responsible for knowing all federal, state, and local laws regarding building, modifying, owning, and using a firearm.

We at GunPros.com are not lawyers and nothing on this page or anywhere else on this website should be considered legal advice. Firearms and firearm parts shown on this page may not be legal to possess or use as part of a firearm where you live.

Be sure to do your own research and seek legal counsel regarding all legalities related to building and owning an AR-15 or any other firearm where you live.

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