How-To Guide for Building an AR-15 thumbnail image

How-To Guide for Building an AR-15

5D Tactical - 20th Jul 2023

The AR-15 style rifle has over the years become of the most popular guns in the U.S. With its accuracy, flexibility, and modularity, the AR-15 can be easily configured for hunting, competition, plinking and self-defense. 

These modifications can be made with simple tools in the comfort of your own home-based garage or workshop. If you’re looking to custom build your own rifle, the AR-15 is a great start.

Building your own AR-15 instead of buying one saves money. But how easy is it to assemble an AR-15 at home? Like many first-time beginners, you might have an idea of how to operate and maintain an AR-15 but lack the knowledge needed to assemble one from purchased parts. Here’s a simplified beginner’s guide on how to build the best AR-15.

Identify Your AR-15’s Primary Purpose

Building an AR-15 rifle from scratch is an investment that will cost you time and money. Before you even think about purchasing an AR-15 assembly kit or specific parts and components for your custom build, think carefully about what you want. What will be the primary purpose of your rifle? What are you going to be using it for most of the time?

If you want a close quarter, self defense rifle, you need to build a compact, lightweight AR-15 that’s fitted with accessory rails for attaching laser sights and lights. To build a competition AR-15 rifle, you’ll need to build one with a heavier and longer barrel and a specialized trigger group to improve shooting accuracy. Hunting ARs should be chambered to handle larger rifle calibers.

In this guide, we’re going to focus on building a high-quality rifle with components selected for a custom appearance and great accuracy. Custom build rifle enthusiasts have a wide variety of AR-15 component options to choose from.

Learning the Custom Build Lingo

Depending on the exact model, an AR-15 can contain up to 100 individual components. If you’re a new builder, you’ll likely find yourself dealing with unfamiliar terminology such as bolt carrier group, forward assist, buffer retainer and names of tools like ejector removal tool, barrel nut alignment gauge and pivot pin depressor. 

While these parts' names may be unfamiliar now, the learning process is gradual. Most people spend a great deal of time browsing through both print and online resources looking for an easy-to-understand set of instructions to help them understand how to build the best AR-15. 

There are many great AR-15 custom build videos explaining the technicalities and basics of building your own rifle as well as the terminologies that you should be aware of. The best knowledge resources should provide straightforward explanation of AR-15 configurations options, must-have tools and build components and assembly steps required to build the rifle. 

Manufacturer guides also provide a more detailed and advanced look at the custom build process, offering a deeper insight into additional rifle configurations, expanded tool kit and tips for troubleshooting and avoiding common build problems.

Where to Start

So now you have identified the purpose for which you’re building your own AR-15 and informed yourself on the basics of assembling an AR-15. What’s next? When it comes to learning how to build the best AR 15, there are different ways to assemble one. 

You can either start building your rifle by assembling all the required parts, by including some pre-assembled parts like or by purchasing a pre-assembled lower and upper receiver to make your custom AR-15. It’s up to you to decide the best way to build your custom AR-15. 

According to most custom build experts and AR enthusiasts, the easiest way to assemble an AR-15 is to attach a pre-assembled upper and lower instead of hunting for each individual component to build your rifle from scratch. If you’re interested in the assembly of AR 15 lower receiver or upper receiver, make sure to get the right compatible parts kit.

Selecting the Right Build Parts

When it comes to shopping for parts, there are numerous bits and pieces to navigate as well as a variety of AR-15 assembly kits and pre-assembled rifle sections that are intended to reduce the time you spend building your custom AR. To ensure you’re buying the highest quality parts, look for an established AR-15 custom build parts supplier and find the parts that meet your needs at the price you can afford. The parts you’ll need for an AR-15 build at home include:

  • Upper receiver and lower receiver and a parts kit for each
  • Buffer, buffer tube and a buffer spring for the extension on the lower receiver
  • Barrel and gas block system
  • Handguards – should be matched with the gas block system
  • Bolt carrier group
  • Fixed or collapsible buttstock
  • Magazines

An important consideration when understanding how to build the best AR 15 is ensuring that you only buy ‘mil-spec’ parts that meet the defined specifications for component material and dimensions. Expect most parts and components listed as ‘mil-spec’ to be compatible. However, you’ll also find part variations and non-mil-spec components that don’t fit together. 

Before making any purchases, make sure that the parts are compatible and ensure that they’re right size with all the correct components. All AR-15 components can be ordered online and be shipped to your home, except for the AR-15 lower receiver.

Getting Your Work Space Ready

The level of preparation you have for your AR-15 custom build will determine how hard or easy your rifle build will be. Yes, getting the right tools might be costly, but the good thing is, most of the tools you’ll need for your custom-build are tools you may already have at your home. The most important thing is having a stable and firm, dirt-free surface that can handle some hammering.

Remember these important tips:

  • Safety Make sure to wear safety glasses to protect your eyes from pins and springs that could fly across the room. A shop apron should also be worn to protect your clothing.
  • Work Space Your working area should have plenty of light. The workbench should be clean and clear of any clutter. Have a gun cleaning and maintenance mat over your working area to keep your build parts in one place.
  • Floor area Since you’ll be working with small pins and springs, it’s likely that some of them may find their way on the floor. Have a clean floor or place some plain covering on the floor. This will make it easier for you to find these small parts in case they fall on the floor.
  • Tools You will need several tools to complete your AR-15 assembly. Having the right tools for the job is a critical part of learning how to build the best AR 15. You should have a sturdy bench, vise and AR-15 block kit, roll pin punch set and pin holders, wrenches and hammers and other tools like a multi-tool and takedown tool.

Building Your AR-15 Rifle

When it comes to selecting rifle components and choosing your manufacturer of choice, you’ll want to start with finding a good lower and upper receiver combination. This is critical for fit and function. The last thing you want is a having loose or binding components. During the actual assembly, it’s important to give attention to detail. 

Expert custom builders recommend that you should pre-fit all receivers, components, controls and detents to ensure easy assembly at every step of the process. Also, check headspace and any fit adjustments and reaming.

The AR-15 can be chambered to fit a wide array of cartridges, in calibers ranging from .20 to .50. Once you’ve chosen a caliber for your rifle’s primary and secondary purposes, you’ll need to choose the appropriate barrel length to fit your needs. 

You’ll also need an upper receiver, and the market has many to choose from. While you can assemble one yourself, buying a pre-assembled upper is the easier way to go and also saves you money because expensive tools can be required to properly assemble and AR-15 upper receiver.

The only part that will need some paperwork to purchase is the lower receiver, which is the only part of the AR-15 custom build that is considered a rifle. As with the upper, you can opt to buy a fully pre-assembled lower or in parts. Savvy builders opt to do their own assembly to learn about how the AR-15 works during the build process.

Inside your lower and upper receivers are the critical parts that make your AR-15 rifle work. Keep in mind that on the topside of your rifle, you’ll need a bolt and bolt carrier, correctly sized for the cartridge you’ve selected. 

Underneath, you’ll also need various pins and springs, and most importantly, the best trigger. Don’t skimp when selecting a trigger. Ensure that you also get a buffer tube that’s designed for a rifle and not an AR pistol.

Here’s are the basics of how to build the best AR 15 at home:

  • Spread out your cleaning and maintenance mat
  • Arrange all the tools on the workbench, so they’re easy to access
  • Arrange the parts on the mat and group your parts together by assembly
  • Refer to the assembly instructions provided with the parts to ensure correct grouping
  • Install the forward assist assembly on your AR-15 upper receiver
  • Install the ejection port cover assembly on the upper receiver
  • Assemble the bolt carrier assembly
  • Assemble the charging handle assembly
  • Install the bolt carrier assembly the charging handle assembly into the upper receiver
  • Install the upper receiver into the action block and tighten it in the vise
  • Install the barrel
  • Install the outer receiver nut and the inner barrel retainer nut in the barrel threads
  • Install the AR-15 rifle gas tube and gas block
  • Install the free float tube handguard
  • Attach your pre-assembled lower receiver assembly to your now complete upper receiver assembly.
  • The assembly of AR 15 lower receiver should not be hard with the provided instructions

Testing Your Final Build

Once you’ve learned how to build the best AR 15 and finally assembled your AR-15 rifle, you need to test it to ensure it’s functional and accurate. There are a few things that you’ll need to do before you even load your gun.

  • Check that the safety works through all the settings
  • Check that the rifle trigger works – pull the trigger slowly and listen to the internal parts
  • Load a single round and fire it
  • Recheck the rifle for any loose parts or damage
  • Disassemble the AR-15, clean it and inspect it after shooting the first several rounds

Expect to tweak your gun a few more times after taking your new home-built AR-15 rifle to the gun range. The key to ensuring a positive experience once you’ve completed your AR assembly is ensuring that every part is assembled as expected by following manufacturer’s instructions.

If you’ve done everything correctly, you should expect your rifle to function reliably for many years. You should also test different ammunition including practice, target, hunting and defense-grade .223 loads with bullets ranging from 55 grains to 77 grains in weight.

Why Do People Opt to Build AR-15 Rifles at Home?

Building an AR-15 Rifle Saves Money

Building your own AR-15 rifle from home saves you money on both basic and premium platforms. However, you need to take into consideration the costs of assembly tools. With the right tools and an equipped workspace, you can build a basic AR-15 under $600 instead of spending between $800 and $1000 buying an off-the-rack rifle. There are affordable AR-15 assembly kits that come with everything you need to complete your build except the lower receiver.

You Can Build Your AR With the Features You Want

This is one of the main reasons why many AR enthusiasts opt to custom build their own rifles at home. As a custom home builder, you can handpick every single spring, pin and screw that goes into your rifle build. This way, you can pretty much control your spending on your custom build. Don’t hesitate to spend on the most important parts. A home assembly also makes it easy to build a rifle with a personalized style and look.

Assembling an AR-15 is Actually Fun

Whether you’re a beginner or an advanced rifle enthusiast, assembling an AR-15 is always an exciting and informative project to engage yourself in. It feels pretty good stepping out onto your local shooting range with a good-looking custom rifle that you fully understand. At least with your first custom build project, you’ll have the know-how to modify your AR-15 or build another one later on.

Build With 5D Tactical Today!

Building your own AR-15 rifle can be a challenging yet rewarding process. With 5D Tactical's easy-to-modify platform, the AR-15 is no doubt the easiest gun to adapt from one purpose to another, and is easy to build, even for beginners. Learning how to build the best AR-15 only requires some hands-on skills to be able to follow simple step-by-step guidelines available online.