How to Build an AR 15: A Step-by-Step Guide

Building an AR-15 rifle from scratch can seem like a daunting task, but with the right knowledge and tools, anyone can do it. Whether you're a gun enthusiast looking to customize your own rifle or someone who wants to learn how to build a firearm, this guide will provide you with everything you need to know.

Before diving into the process of building an AR-15, it's important to understand the various components that make up the rifle. From the lower receiver to the barrel and everything in between, each part plays a crucial role in the functionality of the firearm. Additionally, it's important to consider legal considerations and compliance when building your own rifle, as there are certain regulations that must be followed.

With an understanding of the components and legal considerations, the next step is to prepare your workspace and gather the necessary tools. Once you have everything you need, you can begin the process of assembling the lower and upper receivers, choosing accessories and customizations, and completing the final steps of quality control. With proper maintenance and upkeep, your newly built AR-15 rifle will provide you with years of reliable use.

Key Takeaways

• Building an AR-15 rifle requires an understanding of the various components and legal considerations.
• Proper workspace preparation and tool gathering is necessary for a successful build.
• Assembling the lower and upper receivers, choosing accessories and customizations, and completing quality control are the essential steps in building an AR-15 rifle.

Understanding AR-15 Components

Building an AR-15 requires an understanding of the various components that make up the rifle. This section will provide a brief overview of the components that are necessary to build an AR-15, including the upper and lower receiver parts, barrel and gas system.

Upper Receiver Parts

The upper receiver is the part of the AR-15 that houses the barrel, bolt carrier group, charging handle, and other critical components. The upper receiver is typically made of aluminum and is attached to the lower receiver using pins.

The following are the components that make up the upper receiver:

• Barrel: The barrel is the long, cylindrical metal tube that the bullet travels through. It is attached to the upper receiver using a barrel nut.
• Gas Tube: The gas tube is a small metal tube that runs from the gas block to the upper receiver. It directs the gas from the fired round back to the bolt carrier group.
• Gas Block: The gas block is a small metal block that is attached to the barrel. It is responsible for regulating the flow of gas from the fired round back to the bolt carrier group.
• Bolt Carrier Group: The bolt carrier group is the heart of the AR-15. It is responsible for chambering rounds, ejecting spent casings, and loading new rounds into the chamber.
• Charging Handle: The charging handle is the part of the AR-15 that is used to manually charge the weapon. It is located on the rear of the upper receiver.

Lower Receiver Parts

The lower receiver is the part of the AR-15 that houses the trigger assembly, magazine well, and other critical components. The lower receiver is typically made of aluminum and is attached to the upper receiver using pins.

The following are the components that make up the lower receiver:

• Trigger Assembly: The trigger assembly is responsible for releasing the hammer and firing the weapon.
• Magazine Well: The magazine well is the part of the AR-15 that holds the magazine.
• Buffer Tube: The buffer tube is the part of the AR-15 that houses the buffer and spring. It is responsible for absorbing recoil and cycling the weapon.

Barrel and Gas System

The barrel and gas system are critical components of the AR-15. The barrel is responsible for accurately directing the bullet towards the target, while the gas system is responsible for cycling the weapon.

The following are the components that make up the barrel and gas system:

• Barrel: The barrel is the long, cylindrical metal tube that the bullet travels through. It is typically made of chrome-moly steel or stainless steel.
• Gas Tube: The gas tube is a small metal tube that runs from the gas block to the upper receiver. It is responsible for directing the gas from the fired round back to the bolt carrier group.
• Gas Block: The gas block is a small metal block that is attached to the barrel. It is responsible for regulating the flow of gas from the fired round back to the bolt carrier group.
• Muzzle Device: The muzzle device is the part of the AR-15 that is attached to the end of the barrel. It is responsible for reducing recoil and directing the blast of gases away from the shooter.
• Handguard: The handguard is the part of the AR-15 that surrounds the barrel. It is responsible for protecting the shooter's hand from the heat generated by firing the weapon.

By understanding the various components that make up the AR-15, you can make informed decisions when building your own rifle. Whether you are building a rifle for hunting, competition shooting, or self-defense, having a solid understanding of the components is essential for building a reliable and accurate weapon.

Required Tools and Workspace Preparation

Essential Tools

Before starting the AR-15 build, it is essential to have the necessary tools to ensure a smooth and successful build. The following is a list of tools that are required for the build:

• Vice: A vice is necessary to hold the lower receiver in place while installing the lower parts kit. It is recommended to use a vice block to prevent any damage to the receiver.
• Torque Wrench: A torque wrench is necessary to ensure that the barrel nut is tightened to the correct torque specifications. The torque specification for the barrel nut is typically between 30-80 ft-lbs.
• Punch Set: A punch set is necessary to install various pins and detents during the build process. It is recommended to have a set of roll pin holders to prevent any damage to the pins.
• Safety Glasses: Safety glasses are necessary to protect the builder's eyes from any debris that may be generated during the build process.
• Cleaning and Maintenance Mat: A cleaning and maintenance mat is necessary to protect the work surface from any damage and to prevent any small parts from being lost.

Setting Up Your Work Area

Before starting the build, it is important to prepare the workspace to ensure a safe and efficient build process. The following are some tips to help set up the work area:

• Clear Surface: It is recommended to have a clear and organized work surface to prevent any small parts from being lost. A dedicated workspace is ideal, but if not available, a kitchen table or any other flat surface can be used.
• Well-Lit Area: It is important to have a well-lit area to ensure that the builder can see all the small parts and tools clearly.
• Proper Ventilation: It is recommended to have proper ventilation in the work area to prevent any buildup of fumes from cleaning solvents or lubricants.
• Organized Tools: It is recommended to have all the necessary tools organized and easily accessible to prevent any delays during the build process.

By following these tips, the builder can ensure a safe and efficient build process.

Legal Considerations and Compliance

When building an AR-15, it is important to consider the legal implications and compliance requirements. Failure to comply with state and federal laws can result in serious consequences, including fines and imprisonment.

Background Checks and FFL

When purchasing a complete AR-15 from a licensed dealer, a background check is required to ensure that the buyer is not prohibited from owning firearms. It is important to note that if the buyer purchases a lower receiver from a licensed dealer, the dealer must comply with all federal regulations, including the requirement to have a Federal Firearms License (FFL).

Serial Numbers and Regulations

When building an AR-15, it is important to comply with all regulations regarding serial numbers. A serial number is required for all firearms, including those built from 80% lower receivers.

It is also important to comply with all state and federal regulations regarding the configuration of the AR-15. For example, the AR-15 must comply with the National Firearms Act (NFA) if it has a barrel length of less than 16 inches or an overall length of less than 26 inches.

In summary, when building an AR-15, it is important to comply with all state and federal laws regarding firearms. This includes complying with regulations regarding background checks, FFLs, serial numbers, and configuration.

Assembling the Lower Receiver

When building an AR-15, assembling the lower receiver is a crucial step. It is important to take your time and follow the instructions carefully to ensure a properly functioning firearm. This section will cover how to install the trigger assembly and attach the buffer system.

Installing the Trigger Assembly

The trigger assembly is a critical component of the AR-15 lower receiver. It includes the trigger, safety, and hammer. To install the trigger assembly, follow these steps:

1. Insert the trigger into the trigger well of the lower receiver.
2. Place the hammer into the lower receiver and align it with the trigger.
3. Install the safety selector into the lower receiver.
4. Test the trigger assembly to ensure proper function.

It is important to note that the trigger assembly should be installed with caution and attention to detail. Any misalignment or improper installation can result in a malfunctioning firearm.

Attaching the Buffer System

The buffer system includes the buffer, buffer tube, and spring. It is responsible for absorbing the recoil of the firearm. To attach the buffer system, follow these steps:

1. Insert the buffer spring into the buffer tube.
2. Slide the buffer tube into the lower receiver and align it with the buffer retainer pin.
3. Install the buffer retainer pin and spring.
4. Insert the buffer into the buffer tube.

It is crucial to ensure that the buffer system is installed correctly to prevent malfunctions and ensure the shooter's safety.

In conclusion, assembling the lower receiver of an AR-15 requires attention to detail and careful installation of critical components such as the trigger assembly and buffer system. By following the steps outlined in this section, one can ensure a properly functioning firearm.

Assembling the Upper Receiver

Assembling the upper receiver is the heart of building an AR-15. It requires careful attention to detail and precision, as this is where the bolt carrier group and barrel are housed. The following subsections will guide you through the process of securing the barrel and installing the bolt carrier group.

Securing the Barrel

The first step in assembling the upper receiver is securing the barrel. This involves mounting the barrel to the upper receiver and ensuring it is tightly secured. It is important to note that the barrel must be properly aligned with the gas system and upper receiver to function correctly.

To secure the barrel, you will need to follow these steps:

1. Apply a small amount of anti-seize compound to the threads of the barrel extension.
2. Insert the barrel into the upper receiver and hand-tighten the barrel nut onto the receiver.
3. Use a torque wrench to tighten the barrel nut to the manufacturer's recommended torque specification.
4. Align the gas tube with the gas port on the barrel and insert the gas tube into the upper receiver.
5. Tighten the gas block set screws to secure the gas tube in place.

Installing the Bolt Carrier Group

The next step in assembling the upper receiver is installing the bolt carrier group. This is the heart of the upper receiver and is responsible for loading and firing the ammunition.

To install the bolt carrier group, you will need to follow these steps:

1. Insert the bolt carrier group into the upper receiver, ensuring that the bolt is properly aligned with the barrel extension.
2. Slide the charging handle assembly into the upper receiver and attach it to the bolt carrier group.
3. Install the forward assist assembly onto the upper receiver.
4. Attach the ejection port cover assembly onto the upper receiver.

By following these steps, you will have successfully assembled the upper receiver of your AR-15. Remember to take your time and ensure that each step is completed correctly.

Choosing Accessories and Customizations

When building an AR-15, choosing the right accessories and customizations can make all the difference in terms of performance and aesthetics. Here are some key considerations to keep in mind when selecting your sights, handguards, and stocks.

Selecting Sights and Optics

The first step in choosing the right sights and optics for your AR-15 is determining your intended use. Are you planning on using your rifle for close-range shooting or long-range precision? Once you've established your needs, you can start exploring different options.

Iron sights are a classic choice for AR-15s, and they can be an effective option for close-range shooting. The rear sight and front sight work together to provide a clear picture of your target, but they do require some skill to use effectively.

For those looking for a more advanced option, there are a variety of optics available, including red dot sights, holographic sights, and magnified scopes. Red dot sights are a popular choice for close-range shooting, while magnified scopes are ideal for long-range precision. Holographic sights offer a middle ground, providing both speed and accuracy.

Custom Handguards and Stocks

The handguard and stock are two key components of your AR-15's overall look and feel. When selecting these customizations, you'll want to consider both your personal preferences and your intended use.

Drop-in handguards are a popular option for those looking for a quick and easy upgrade. They can be easily installed without any special tools, and they come in a variety of materials and styles. Keymod and M-LOK are two common attachment systems for drop-in handguards, allowing for easy customization with a wide range of accessories.

For those looking for a more traditional option, the A2 handguard is a classic choice. It is made from durable mil-spec materials and provides a comfortable grip. However, it does not offer the same level of customization as drop-in handguards.

When it comes to stocks, there are a variety of options to choose from, including adjustable and fixed stocks. Adjustable stocks allow for greater flexibility in terms of length of pull, while fixed stocks provide a more traditional look and feel. Picatinny rails can also be added to the stock for attaching additional accessories.

Overall, choosing the right accessories and customizations for your AR-15 is an important step in building a rifle that meets your needs and preferences. By considering your intended use and exploring different options, you can create a rifle that is both functional and stylish.

Final Steps and Quality Control

Inspecting and Testing

Once the AR-15 rifle is assembled, it is important to inspect and test it to ensure that it is functioning properly. The following are some of the key steps to take:

• Inspect the rifle for any visible defects or damage. Check the finish, length, and alignment of the components to ensure that they are within specifications.
• Test the trigger pull to ensure that it is smooth and consistent. The trigger pull weight should be within the desired range.
• Check the accuracy of the rifle by shooting it at a target. The rifle should be able to shoot consistently and accurately at the desired distance.
• Check the velocity of the rifle by using a chronograph. The velocity should be within the desired range for the caliber and twist rate of the barrel.

Finishing Touches

After inspecting and testing the rifle, there are a few finishing touches that can be added to improve its performance and appearance:

• Install a muzzle brake or flash hider to reduce recoil and muzzle flash. This can improve accuracy and make shooting more comfortable.
• Apply a protective finish to the rifle to prevent rust and corrosion. This can also improve the appearance of the rifle.
• Add accessories such as a sling, optics, or a bipod to customize the rifle for the shooter's needs.

By following these final steps and performing quality control checks, the builder can ensure that their AR-15 rifle is functioning properly and meets their desired specifications.

Maintenance and Upkeep of Your AR-15

Once you have built your AR-15, it is important to maintain it regularly to ensure its longevity and reliability. A regular cleaning and maintenance routine can also help prevent malfunctions and keep your firearm in top condition.

One essential tool for maintaining your AR-15 is a cleaning and maintenance mat. This will provide a clean and safe surface to work on your firearm, protecting it from scratches and other damage. It is also recommended to use a build kit that includes all the necessary tools and cleaning supplies.

Regular maintenance includes cleaning the barrel, bolt carrier group, and other components of the firearm. It is important to use a high-quality cleaning solvent and lubricant to ensure that the firearm operates smoothly and reliably. A dirty or dry firearm can lead to malfunctions and decreased accuracy.

In addition to regular cleaning, it is also important to inspect your AR-15 for any signs of wear or damage. This includes checking the gas system, trigger, and other components for any signs of wear or damage. If you notice any issues, it is important to address them immediately to prevent further damage and ensure the reliability of your firearm.

Overall, maintaining your AR-15 is essential for its longevity and reliability. By following a regular cleaning and maintenance routine, using high-quality cleaning supplies and tools, and inspecting your firearm regularly, you can ensure that your AR-15 will operate smoothly and reliably for years to come.

Frequently Asked Questions

What are the legal requirements for assembling an AR-15 at home?

The legal requirements for assembling an AR-15 at home vary by state and jurisdiction. However, it is generally legal to build an AR-15 for personal use without a Federal Firearms License (FFL) as long as the builder is not prohibited from owning firearms and the rifle complies with state and federal laws. It is important to research and understand the laws in your area before starting an AR-15 build.

Is it possible to construct an AR-15 without a Federal Firearms License?

Yes, it is possible to construct an AR-15 without a Federal Firearms License (FFL) as long as the builder is not prohibited from owning firearms and the rifle complies with state and federal laws. However, if the builder intends to sell or transfer the rifle, they must obtain an FFL or transfer the firearm through a licensed dealer.

What are the advantages of building an AR-15 compared to purchasing one?

Building an AR-15 allows the builder to customize and tailor the rifle to their specific needs and preferences. It also provides a deeper understanding of how the rifle functions and can be a rewarding experience. Building an AR-15 can also be more cost-effective than purchasing a pre-built rifle.

Which specific tools do I need to assemble an AR-15 from scratch?

To assemble an AR-15 from scratch, the builder will need several specific tools, including a vise, torque wrench, armorer wrench, punch set, and a bench block. It is important to use high-quality tools to ensure a safe and successful build.

What are the essential components required to build a functional AR-15?

The essential components required to build a functional AR-15 include a lower receiver, upper receiver, barrel, bolt carrier group, charging handle, buffer tube, buffer spring, buffer, trigger assembly, and handguard. It is important to use high-quality components from reputable manufacturers to ensure a safe and reliable rifle.

How do I ensure that my AR-15 build complies with state and federal laws?

To ensure that an AR-15 build complies with state and federal laws, it is important to research and understand the laws in your area before starting the build. The rifle must comply with all applicable laws regarding features such as barrel length, overall length, and magazine capacity. It is also important to perform a function check and ensure that the rifle is safe and reliable before firing.