AR-15 Parts List for Building your Own Rifle

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Building your Own Rifle

One of the best things about AR-15s is that they are highly customizable, and one can build their own. Building an AR-15 is neither a simple process nor a complicated one if you are knowledgeable on the basic AR-15 parts and skill on how to assemble and disassemble a gun. You can also enhance your skills by checking on many available AR-15 build guides on both rifles and pistols.

Depending on the kind of AR-15 you want, you can build an AR-15 within a budget of as low as $400 and more. However, the most significant factor to consider if you want a reliable and high performing AR-15 is the quality of your AR-15 parts. For that reason, this article is a guide listing all AR-15 parts needed for an AR-15 build.

Let’s see what parts you needed and their functions in an AR-15.

List of AR-15 Parts: AR-15 Build List

An AR-15 comes into two main components, irrespective of it being a rifle or a pistol variant. They include the upper and lower receiver. Each of these components comprises other individual parts, and when joined together, you get a fully assembled AR-15 gun.

AR-15 Upper Receiver Parts

Below parts make up the AR-15 upper receiver when assembled together. Additionally, it’s followed by precise details of their functions. It’s what you need while building your own AR-15 rifle.

1. Upper Receivers

An upper receiver is a metal piece that houses the charging handle, bolt carrier group, and an attachment point for the barrel. Depending on what you want, you can select between a stripped upper and a complete upper receiver.

A complete AR-15 upper comes with ejection port assembly and forward assist already installed. For the stripped, you will have to install the parts. However, if you decide to go with the stripped version, you will need to buy an AR-15 upper parts kit. This kit entails the dust cover and the forward assist.

2. Bolt Carrier Group (BCG)

It’s a vital part of the AR-15 made up of the bolt, gas key, extractor, cam pin, and firing pin. It helps in ejecting spent cartridges out of the chamber and chambering new rounds. Also, it ensures the rounds are fired in the right manner from the chamber. It comes either as pre-assembled or as a kit containing all of the parts named above whereby you assemble it.

3. Charging Handle

This part functions closely with the BCG. It moves the charging handle to the rear to clear a malfunction of the rifle or chamber a new round when pulled. It’s offered in two designs, i.e., the single lever or ambidextrous charging handle.

4. Barrel Assembly

This assembly must include the barrel itself and the barrel nut. Barrels differ widely depending on your suitable length, caliber, and twist rate. Also, they are made of different materials.

For a rifle, your barrel must be more than 16 inches long.  However, the short-barreled rifle has a barrel less than 16 inches, but the law requires you to pay for the tax stamp and fill all the necessary paperwork. The barrel nut attaches the barrel to the receiver

5. Gas block and Gas Key

These two parts work together. The gas block directs gas directly to the gas tube and then channeled back to the upper receiver. Gas blocks come either as fixed gas block or adjustable gas blocks.

6. Muzzle Device

This part is fixed on the barrel’s front end to deal with recoil, flash, and sound from your AR-15 rifle. It can be a flash hider or muzzle brake. However, you may get a combo muzzle device designed to handle the two functions altogether.

7. Handguard

This particular part protects your hands against heat from the barrel and provides attachment slots for other AR-15 accessories such as flashlights, sights, bipods, slings, etc.

It’s offered in different designs, i.e., free-float handguards or drop-in handguards. The handguard’s attachment can also adopt any of these styles: M-LoK, Picatinny, or KeyMod.

Related Article: What are the 10 rules of Golden Gun Safety?

AR-15 Lower Receiver Parts

Here is a list of AR-15 lower receiver assembly that you need while building an AR-15 rifle. It also highlights their functions.

1. Lower Receiver

This part is a frame that houses all other parts of the lower receiver assembly. It can either come as stripped or 80% polymer lower. For the stripped lower, you will have to undergo a background check and pay some fee. On the other hand, the 80% lower requires you to complete it through milling to get a 100% complete receiver.

2. Buffer Tube Assembly

It’s made up of the buffer, buffer spring, and buffer tube itself. A buffer tube houses the buffer and buffer spring. Also, it offers an attachment for the stock. The buffer is liable for recoil absorption of the rifle and slows down the bolt. Lastly, the buffer spring also works with the bolt to allow follow up shots.

Like many other parts, this assembly comes in different sizes for Mil-Spec, Carbine, or commercial specs.

3. Butt Stock

This part of the lower receiver provides support structural support to the rest of the rifle, and most importantly, it allows you to shoulder your AR-15 while firing.

AR-15 stocks are of different types. They include fixed, minimalist, collapsible, folding, and adjustable stocks. Select what works with your rifle and needs.

4. AR-15 Lower Parts Kit

This kit has many parts that you must have on your table before building your AR-15 rifle. The most convenient way to have all of them is by purchasing a kit.

Among the significant parts from the kit includes a bolt catch, springs, pivot pins, takedown pins, the trigger, hammer, and selector switch. However, some of the parts you might not need them.

For the trigger and the grip, you may select different designs of your choice. There are many options available in the market suitable for different AR-15 rifle shooters.

5. Fire Control Group

As mentioned above, you should consider purchasing the trigger group, i.e., the hammer, trigger, and fire control, separately.

Quality trigger group parts can easily enhance the shooting experience with the AR-15 rifle and the accuracy.

6. Magazine

Your AR-15 can be complete if you don’t have a magazine to hold your rounds. It’s where they are loaded before the chambering. Magazines also come in different sizes.


Building your own AR-15 is an exciting experience when you have all the parts and quality AR-15 parts. You must also have tools such as a Vice, Vice blocks, Roll-Pin pusher, Armorer’s wrench, and Roll pin set.

Additionally, building an AR-15 rifle from scratch helps you understand better your gun’s parts and mechanism. Enjoy!

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