Building an AR-15 Guide

Building an AR-15 Guide: All the Parts You Are Going to Need

Building an AR-15 is one of the greatest things that you can do to improve your confidence and knowledge with these firearms, and when it is all said and done you have a rifle that is unique to you. So where do you begin if you want to build an AR-15?

A great place to start would be to have a complete parts list of everything that you are going to need. Luckily, you have come to the right place! Let’s go over every gun part you will need for a new build, and a little about each one!

Stripped Lower

Stripped lowers can be found just about anywhere you buy firearms, and you will not find a huge difference between the expensive ones and the average ones. Just try to purchase one from a brand that you like, or one that you enjoy the design of. The lower receiver is the base of your entire gun build, so make sure it is something that you will enjoy looking at in the future.

Lower Parts Kit

The lower parts kit goes along with a stripped receiver and includes all of the springs and pins that go inside of the lower, as well as all of the hardware that is needed for it to function. Some of these kits come with a trigger, others don’t. Many include a basic mil-spec trigger, so if you want an upgrade you will need to get that separately.


Again, this might be included in the lower parts kit but it is always good to spend a little extra money for increased accuracy. Triggers will come in all different shapes, sizes, and price points, so you will have plenty of options to choose from.

Buffer Kit

A buffer kit will install a buffer system that manages the recoil of the gun and helps it to properly cycle. There are different buffer weights to be aware of, so do some homework into choosing the proper buffer system for your rifle.


The stock of a rifle is another part that has plenty of different options, from high end stuff to basic, no frills mil-spec. There are millions of brands out there to choose from, so pick one that you like and one that suits the purpose of the rifle.

Stripped or Assembled Upper

A stripped upper is simply just the upper, while an assembled upper will come with a forward assist and a dust cover. A complete upper will come with all of this, including a barrel and handguard as well. It all comes down to how much assembling and customization you want to do.

Forward Assist

Forward assists will help put a gun back into battery if need be, although they are really not used that much. Many uppers will already come with a forward assist included.

Dust Cover

Dust covers (also called ejection port covers) help to keep dust out of the inside of your rifle. Again, this might already come included on your upper but there are plenty out there with many different designs on them.


The barrel is easily going to be one of the most important parts of your rifle, and affects the accuracy and performance of the firearm more than anything else. Barrels give you lots of options, from twist rate, length, steel type, linings, and more. Again, try to choose a barrel that is suited for your intended use.


The handguard goes around the barrel and helps to protect your hand from the heat that is generated from firing, as well as giving you a comfortable area to place your hand. This is a big personal preference part, and again there are thousands of options to choose from. If you want something lightweight, you can go with that. Want a lot of places to mount accessories? There are handguards that excel with that.

Gas Tube

A gas tube is part that helps to transport gas through the gun, making it cycle. As a round is fired, the gases that are released go up through the gas tube. This inertia is then utilized to eject the spent round, and cycle in a new one. Gas tubes should match the barrel’s system length.

Gas Block

The gas block is a simple component that fits over the small hole on the top of an AR-15’s barrel that allows the gases to escape. It works in conjunction with the gas tube and holds it in place. Most shooters will be perfectly fine with a regular gas block, but if you might run a suppressor then you might look into an adjustable gas block

Bolt Carrier Group

The bolt carrier group is the part of the gun that does the actual firing and extracting of your ammunition. The lighter and smoother this part is, the better. With a lighter bolt carrier group, the less recoil and muzzle movement you will experience, resulting in better accuracy. The smoother your bolt carrier group, the more consistent and reliable the firearm will be.

Charging Handle

The charging handle helps you to chamber a new round in your gun. With a basic AR build, a standard charging handle will suit you just fine. Of course, you can go with an upgraded version that extends further, is larger for better grip, and even some that have an ambidextrous handle.

Muzzle Device

Some barrels may already include some sort of muzzle device, others won’t. There are many different types of muzzle devices that you can use, such as compensators, muzzle brakes, flash hiders, and even suppressors. This decision will come down to what you intend to use your gun for and what kind of performance you want out of it.

Final Thoughts

Building an AR-15 may seem like it will take a lot of parts and be complicated, but in fact it is pretty simple. With a little bit of practice and some patience, practically anyone can build their own AR-15 that they can be proud of!

Also read: 5 Reasons to Build Your Own AR-15 Rifle Instead of Buying

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