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How to Build an AR-15

Why Build an AR-15?

Completely assembling your firearm is an experience that you can’t often get with other firearms, especially pistols. Thanks to the well established standards of “mil-spec,” building your own AR-15 is a very easy process which requires minimal knowledge/experience and only basic tools. Building your own AR-15 allows you to:

  1. Learn about the inner workings of the rifle
  2. Be better prepared to handle rifle malfunctions and general maintenance
  3. Save money
  4. Custom tailor the AR-15 to your exact specifications

1 & 2: Learn more about the AR-15

While assembling the AR-15, you get to handle and piece together each and every part. When you build your first AR-15, this gives you the opportunity to understand how every part works together to operate a semi automatic rifle. This provides knowledge that aids in clearing malfunctions, and all around maintain the rifle.

3: Save money

Thanks to the over abundance of aftermarket AR-15 parts, finding what you need is incredibly easy. This allows shoppers to find exactly what they need for a real good price. With a little bit of research and planning, it is very easy to build an AR-15 for less than the cost of an assembled AR-15. This allows shooters to up the build quality or buy more ammo. After all, what’s the point of owning an AR-15 if you don’t have ammo to shoot?

4: Custom tailor your AR-15

AR-15s are often jokingly called “Legos for men.” It’s not that far off. Due to the AR-15’s popularity, the amount of parts options can be very daunting. But that provides an excellent opportunity to find anything at all to meet your needs! Such as… budget parts, high end quality parts, unique details to suit your specific rifle use case, or even impractical parts that simply look awesome.

AR-15 Parts List

While there are many build kits that come with everything you need except for a lower receiver, hand selecting each and every part for an AR-15 build allows shooters to have an entirely unique AR-15 custom tailored for the owner.

This parts list is to help new AR-15 builders to find exactly what is needed.

AR-15 Upper Parts

When selecting a barrel, pay attention to the gas length. A gas tube must match the barrel. Most AR-15 barrels are carbine length, but rifle length gas tubes are common on longer barrels and pistol length gas tubes on shorter barrels.

Also keep in mind, a rifle barrel must be at least sixteen inches to avoid the NFA classification of a short barrel rifle. However, if a short barrel is matched with an AR-15 pistol lower, then it is legal. Thank the ATF for that convoluted logic.

AR-15 Lower Parts

  • Lower Receiver – this is the serialized firearm part that must be purchased through a FFL
  • Lower Parts Kit, usually includes, but doesn’t always, and can be purchased separately:
  • Buffer Tube Kit, usually purchased as a kit, but can be purchased individually
    • Buffer
    • Buffer Spring
    • Castle Nut
    • End Plate
  • Stock

When acquiring your AR-15 build, be sure to read up thoroughly on every part you purchase. For example, most AR-15 lower parts kits come with all of the assorted springs, triggers, and screws needed to assemble a complete AR-15 lower receiver. However, it is possible to buy a lower parts kit without a trigger or pistol grip to hand select a pistol grip and trigger. Similarly, some upper receivers don’t always come with dust covers or forward assists.

Quick disclaimer: This parts list is a list of parts to be purchased and assembled. It’s not a comprehensive list of every part in an AR, as some of these parts are always bundled in various kits.

Tools to Assemble and Maintain an AR-15

AR-15s can be assembled with minimal tools, though there are various optional tools that make it easier. The Wheeler AR Armorer’s Professional Kit or AR Armorer’s Essentials Kit are great places to start.

Minimum required tools
Helpful, but not required

If you don’t want to get the parts piece by piece, Wheeler has an Ultra AR-15 Armorer’s Kit, Professional AR-15 Armorer’s Kit, and Essentials Armorer’s Kit.

How to Build the AR-15 Lower

How to Build the AR-15 Upper

Brian Purkiss
Written by

Brian Purkiss is a Christian, husband, competitive shooter, firearms instructor, proponent for individual liberty and Second Amendment rights, and a web developer. He primarily focues on USPSA and Run & Gun competitions, but enjoys most other forms of shooting competitions as well.

Categories: Firearms, Vault

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