AR Build Upper and Lower Receiver – 5 Easy Steps & Benefits

AR Build Upper and Lower Receiver

June 12, 2023 / Comments (0)

AR Build

In the world of firearms, the AR-15 platform has gained immense popularity for its versatility and customization options. One of the key aspects of an AR-15 build is the upper and lower receivers.

These receivers house vital components of the firearm and play a crucial role in its overall functionality.

This article will provide a step-by-step guide on building an AR build upper receiver and a lower receiver, allowing you to create a firearm tailored to your preferences.

Introduction to AR Build Upper and Lower Receiver

Before diving into the specifics, let's clarify an AR build's upper and lower receiver. The upper receiver is the uppermost part of the AR-15, which contains the barrel, gas system, handguard, and other crucial components.

On the other hand, the lower receiver houses the trigger assembly, magazine well, and stock, among other components.

These receivers are the foundation of the AR-15 build and provide the framework upon which other parts are assembled.

AR build upper receiver

Building your own AR receiver offers several advantages over purchasing a pre-assembled firearm. It allows you to customize your firearm to suit your needs and preferences.

Additionally, building an AR-15 can be a rewarding and educational experience, providing a deep understanding of how the firearm functions.

AR Build Upper and Lower Receiver

The Upper Receiver

The AR build upper receiver consists of various components that work together to ensure the proper functioning of the firearm.

Understanding these components is crucial when building your upper receiver. Here are some key aspects to consider:

Components of Upper Receiver

The upper receiver assembly includes the following components:

  • Barrel: The barrel guides the bullet and determines its accuracy and range.
  • Gas System: The gas system directs the gas generated by firing a round to cycle the firearm's action.
  • Handguard: The handguard provides a gripping surface and protects the shooter's hand from the barrel's heat.
  • Bolt Carrier Group (BCG): The BCG is responsible for chambering rounds, extracting spent casings, and cocking the hammer.
  • Charging Handle: The charging handle allows users to cycle the action manually.
  • Forward Assist: The forward assist helps seat the bolt in the chamber if necessary.
  • Dust Cover: The dust cover protects the internal components from dirt and debris.

Different Types of Upper Receivers

Different types of upper receivers are available, each with unique features and advantages. The most common types include:

  • A1/A2 Upper Receiver: These classic mil-spec upper receivers feature fixed carry handles and iron sights.
  • Flat-Top Upper Receiver: The flat-top upper receiver lacks a carry handle and offers a Picatinny rail, providing ample space for mounting optics, sights, or other accessories.
  • Stripped Upper Receiver: A stripped upper receiver lacks most components and allows you to customize your build by selecting each part individually.

The Lower Receiver

The AR build lower receiver is equally important and houses critical components such as the trigger assembly and stock. Let's take a closer look at the lower receiver:

AR build upper receiver

Components of the AR Build Lower Receiver

The lower receiver assembly includes the following components:

  • Lower Receiver:  The lower receiver serves as the core of the AR-15 and holds all other components.
  • Trigger Assembly: The trigger assembly consists of the trigger, hammer, disconnector, and springs, and it controls the firing mechanism.
  • Magazine Well:  The magazine well allows the insertion and retention of magazines.
  • Stock:  The stock provides stability and support for the shooter, enhancing accuracy and comfort.
  • Pistol Grip: The pistol grip is where the shooter's hand holds the firearm and allows for better control.

Different Types of Lower Receivers

Similar to upper receivers, there are different types of lower receivers available. The two main types are:

  • Mil-Spec Lower Receiver:  These lower receivers adhere to military specifications and are compatible with most AR-15 parts.
  • Billet Lower Receiver:  Billet receivers are machined from a solid aluminum block, allowing for more intricate designs and customization options.

Building an AR Upper Receiver

Building an AR upper receiver requires attention to detail and a systematic approach. Here's a step-by-step guide to help you through the process:

Selecting the Right Upper Receiver Kit

Start by choosing an upper receiver kit that suits your needs and preferences. Consider factors such as barrel length, handguard type, and gas system.

Installing the Barrel and Gas System

Carefully install the barrel into the upper receiver and secure it using the barrel nut. Install the gas tube and block, ensuring proper alignment and secure attachment.

Assembling the Bolt Carrier Group

Prepare the bolt carrier group by inserting the bolt into the carrier. Apply lubrication per the manufacturer's instructions and install the assembly into the upper receiver.

Installing the Charging Handle and Handguard

Attach the charging handle to the upper receiver, ensuring smooth operation. Install the handguard of your choice, following the manufacturer's guidelines.

Attaching the Upper Receiver to the Lower Receiver

Align the upper receiver with the lower receiver and insert the takedown pins to secure them together. Perform a function check to ensure proper alignment and functionality.

Building an AR Lower Receiver

Building the AR build lower receiver is a meticulous process that requires careful attention to detail. Follow these steps to assemble your lower receiver:

Understanding the Lower Receiver Parts

Familiarize yourself with the different parts of the lower receiver, including the magazine well, trigger assembly, and stock components.

Installing the Lower Receiver Parts

Install the trigger guard, magazine catch, bolt catch, and pivot pin into the lower receiver. Ensure each part is properly aligned and securely attached.

Installing the Trigger Assembly

Carefully install the trigger assembly, ensuring proper engagement and smooth operation. Follow the manufacturer's instructions for adjusting the trigger pull weight if desired.

Installing the Buffer Tube and Stock

Attach the buffer tube to the lower receiver, then install the buffer spring and buffer. Finally, install the stock onto the buffer tube, securing it firmly.

Function Testing and Safety Checks

Perform a function test on the completed lower receiver, ensuring proper operation and safety. Check for any abnormalities and address them accordingly. Remember to follow all safety protocols throughout the process.

Benefits of Building AR Receiver

Building your AR receiver offers several advantages, making it an appealing option for firearm enthusiasts. Some key benefits include:

  • Customization Options: Building your AR receiver allows you to select each component according to your preferences, resulting in a firearm that suits your needs.
  • Cost Savings: By purchasing individual parts and assembling them yourself, you can often save money compared to buying a pre-assembled firearm.
  • Knowledge and Understanding of Your Firearm: Building your AR receiver provides valuable insight into the inner workings of the firearm, enhancing your knowledge and understanding of its functionality.
AR build upper & lower receiver

Safety Considerations When Building an AR Receiver

While building an AR receiver can be a rewarding experience, it's crucial to prioritize safety throughout the process. Here are some important safety considerations:

  • Following Proper Safety Procedures: Always adhere to safe firearm handling practices, including unloading the firearm until ready for use and following all local, state, and federal laws.
  • Adhering to Legal Requirements: Ensure that your build complies with all applicable laws and regulations regarding firearm assembly and possession in your jurisdiction.

Building your own AR build upper receiver and AR build lower receiver can be fulfilling, allowing you to create a firearm tailored to your preferences.

Following a step-by-step process and prioritizing safety, you can assemble a high-quality AR-15 that meets your needs and offers a deeper understanding of its functionality. Enjoy the journey of building your AR receiver, and always remember to prioritize safety.

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