DIY AR-15 Upper Assembly: A Step-by-Step Guide

Building your own AR-15 upper assembly is a rewarding project for firearm enthusiasts who enjoy customization and want to better understand their rifles. This step-by-step guide will help you assemble the upper receiver of your AR-15.

Tools and Safety

Before you begin, ensure you have the necessary tools and follow firearm safety rules:

  • Safety glasses and ear protection
  • Vise block or AR15 Parts  receiver vice block
  • Armorer’s wrench
  • Torque wrench
  • Barrel nut wrench
  • Roll pin punch set
  • Mallet
  • Vice or workbench
  • AR-15 upper receiver, barrel, handguard, bolt carrier group, charging handle, and necessary parts and tools

Step 1: Barrel Installation

  1. Place the upper receiver in a vise block or upper receiver vice block to secure it in a vice or workbench.
  2. Apply a small amount of anti-seize lubricant to the threads of the barrel and the upper receiver’s barrel extension.
  3. Carefully insert the barrel into the upper receiver, ensuring the barrel extension aligns with the upper receiver’s ejection port.
  4. Hand-tighten the barrel nut onto the upper receiver threads.
  5. Use an armorer’s wrench to torque the barrel nut to the manufacturer’s specified torque value, usually around 30-80 ft-lbs. Check the rifle’s manual or the manufacturer’s instructions for the exact torque value.

Step 2: Gas System and Handguard

  1. Install the gas block and gas tube onto the barrel.
  2. Slide the handguard over the barrel and secure it using the provided hardware or attachment method specific to your handguard.
  3. Ensure the gas tube lines up with the gas key on the bolt carrier group. Adjust the gas block as needed.

Step 3: Forward Assist and Dust Cover

  1. Install the forward assist assembly by pushing it into the corresponding slot in the upper receiver. Secure it with the roll pin using a roll pin punch and mallet.
  2. Attach the dust cover to the upper receiver using the hinge pin.

Step 4: Bolt Carrier Group and Charging Handle

  1. Slide the bolt carrier group into the upper receiver, ensuring the bolt aligns with the barrel extension.
  2. Install the charging handle into the upper receiver, connecting it to the bolt carrier group.

Step 5: Final Checks

  1. Double-check that all components are properly aligned and secured.
  2. Ensure the upper receiver and barrel are clean and free of debris and lubricate the necessary components.

Step 6: Function Test

Perform a function test to ensure all parts are working correctly. Ensure the bolt carrier group cycles, the safety functions properly, and the trigger resets as expected.

Step 7: Final Inspection

Thoroughly inspect your upper assembly for any issues or loose components. Once satisfied, your DIY AR-15 upper assembly is complete, and you’re ready to attach it to a lower receiver for a fully functional rifle. Always follow local, state, and federal laws and regulations when building or modifying firearms.

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