The AR-15 semi-automatic rifle was first designed by Armalite in 1956. It was then sold to Colt in 1959, who sold it as a civilian counterpart to the military M4. Once Colt’s patent expired in 1977, a variety of other companies began to construct AR-15-style rifles. Today, firearms using this model are made by many different manufacturers. AR-15s are also a common choice for those who enjoy assembling their own guns. Building an AR-15 is easier than many would assume and it is a great way to create a fully-customized weapon.
In order to build your own AR-15, you will need to understand the basic parts of this rifle.
AR-15 Lower Receiver
The lower receiver is the part of the rifle that includes the fire control group, magazine well, and pistol grip. It can be forged (hammered into shape) or billet (milled into shape). Forged receivers are stronger, whereas billet receivers are lighter but slightly weaker.
The lower receiver is the only AR-15 part that is legally considered a firearm. This means that it has a serial number and specific regulations govern its purchase. Some builders prefer to purchase an 80% lower receiver which is not legally considered a firearm. This is an unfinished version of the part and it’s not able to fire without milling. It requires more work to finish an 80% lower receiver, but this is more customizable and may involve fewer fees than purchasing a full lower receiver.
You will also need to buy lower receiver parts, which include: a trigger assembly, trigger guard, magazine catch/release, bolt catch/release, safety selector switch, grip, takedown pins, receiver extension (buffer tube), buffer and spring, and buttstock. You can purchase these in a kit or separately.
Upper Receiver
The AR-15 upper receiver houses and protects the components on the top of your rifle. It can be flat top or carry handle. A flat top receiver has a Picatinny railing at the top, whereas a carry handle receiver has a rear sight assembly in this location. This part can be forged, billet, or cast. Cast is the lightest option, but it is also the weakest. You can purchase a stripped upper, which contains only the upper receiver and will require more parts to complete. If you prefer, you can purchase a complete upper, which only needs to be attached to a lower receiver. Parts in the upper receiver group that you will need to attach to a stripped upper include the charging handle, barrel, handguard, and bolt carrier group.
Gas System
Guns fire by using high-pressure gas generated through a gunpowder explosion to propel a bullet. Some of the pressure also ejects the spent cartridge and brings a new one into the chamber. AR-15 rifles use a direct impingement system, meaning that a “gas port” on the chamber vents hot gas into a tube and brings it back to the receiver to automatically cycle the next round. When you build your own AR-15, you will choose the length of the gas block, which is the length between the gas port and the receiver. You should choose the gas system length based on the length of your barrel. From shortest to longest, your options are carbine, mid-length, and rifle.
Furniture and Accessories
Once the functional components of your AR-15 are in place, you will want to add furniture and accessories. Furniture refers to the parts of your gun that you hold/support and includes the stock, grip, and handguard. You will want to pick these based on what feels best for you. Accessories are any other parts to enhance your gun such as scopes or lights.
The Hub, Your Arizona Gun Store
We Can Help You Build Your New AR-15
At The Hub, we specialize in AR-15-style rifles. We carry many versions of these firearms at our Tucson and Lakeside locations and online. We are also happy to help you if you wish to build your own. Our store carries the different AR-15 parts you will need and if we don’t have what you need in stock, we can help you locate it.
