AR Rifle Parts | Building a Rifle From Start to Finish

There’s no better way to customize your AR than with a DIY kit. Good kits will contain all the parts and tools you need to complete your gunsmithing build at home without the hassle of excessive paperwork.

Check out our definitive guide on how a DIY rifle kit works from start to finish so you can get building right away.

man dressed in camouflage outdoors holding a rifle

Decide What Type of Rifle You Want to Build

Part of the beauty of ARs is how versatile they are. You can customize almost every aspect of these firearms with various AR rifle parts, accessories, finishes, and more.

Do you want a carbon or stainless steel barrel? Will you go with the common Picatinny handguard or a lesser-used but still good quality Keymod or M-LOK? Do you prefer a normal scope or do you want a red dot sight?

In addition to the incredible selection of parts, what you’ll use your gun for will affect what kind of kit you purchase. Are you building an AR for hunting? Sharpshooting? Home defense? Whatever the purpose, figure out what it is before purchasing your AR rifle parts so your gun will function exactly as you need it to.

Take Stock of Your Tools

While there are some specialized tools you’ll need to build your rifle, you may already have a few of the necessary pieces of equipment at home, like a general torch wrench. Take stock of your current tools before purchasing a kit to ensure you’re not buying something you already own.

In addition to your AR rifle parts, you’ll need a jig and a set of mill tools. The jig is the portable workstation that will enable you to drill with the milling tools and turn your 80% lower receiver into a legal firearm.

80% Lower Receivers

All rifles worth building start with a quality 80% lower receiver. Whether you’re building an AR-10 or an AR-15, look for 80% lower receivers made of aircraft-grade, forged 7075t6 aluminum with a hard coat of anodizing. Anodizing the receiver thickens the natural oxide, giving the receiver enhanced durability.

80 percent lower receiver for AR 10

In addition to the 80% lower receivers, you’ll need a kit with the rest of the AR rifle parts: the upper receiver, barrel, bolt carrier group, gas system length, handguards, and more.

Make sure your kit matches your gas system length and barrel length. Too much barrel can result in gas leakage, while too little means there won’t be enough force to unlock the bolt.

Building the Rifle

Before you build, prep your work area. Make sure you have safety glasses on hand, and a shop apron to protect your clothes if you want. Lay down a mat to keep parts from rolling around and ensure your space is well-lit. If possible, it’s helpful to lay a white covering over the floor for when small pins or springs inevitably fall.

Assemble your AR rifle parts and all the necessary tools. You’re ready to build.

Keep in mind that the steps below will vary greatly depending on the factors we discussed above. But generally speaking:

  1. Put together the forward assist assembly and insert it in the upper receiver.
  2. Install the ejection port cover assembly on the upper receiver.
  3. Put together the bolt carrier assembly.
  4. Put together the charging handle assembly.
  5. Install both the charging handle assembly and the bolt carrier assembly into the upper receiver.
  6. Install the upper receiver in the action block and tighten it with a vise.
  7. Install the barrel, including the outer receiver nut and inner barrel retainer nut on barrel threads.
  8. Install the gas tube and gas block, and then the free float tube handguard.
  9. Put your upper receiver assembly and lower receiver assembly together.

Again, this is obviously a fairly general set of directions. Your AR rifle parts and the process to assemble it will vary greatly depending on the kit you purchase. If your kit comes with manufacturing instructions, follow those for more detail.

Shop AR Parts and Kits at JSD Supply

Get started on your next build with quality parts and kits from JSD Supply. We’ve been providing gunsmiths with everything they need to build firearms from the comfort and privacy of their own homes since 2013. You can trust our parts because we use them too. Contact us with questions about your building a rifle or use our Live Chat feature for help choosing AR rifle parts today.