How to Replace a Barrel in an AR15

The AR15 semi-automatic rifle is derived from the design of the military M16. AR15-style rifles are sold on the civilian market under a variety of brand names. However, many of the components are interchangeable and the takedown procedure for basic repair and replacement is the same for most models. Since the AR15 is based on a design intended for battlefield use, large component replacement such as switching barrels has been reduced to a few simple steps and can be accomplished quickly without major disassembly.

Things You'll Need

  • AR15 vise block
  • AR15 armorer's tool
  • Torque wrench
  • Molybdenum disulfide grease
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Instructions

  1. Barrel Removal

    • 1

      Make sure the rifle is unloaded by removing the magazine, operating the charging handle and visually verifying that the weapon is empty.

    • 2

      Remove the handguards by pulling down on the spring-loaded delta ring at the base of the handguards to release the mounting tabs.

    • 3

      Push out the gas tube roll pin located in the front sight base. Slide the gas tube out.

    • 4

      Push the front and rear take-down pins out from the left side of the receiver to the right. Separate the upper receiver from the lower receiver.

    • 5

      Install the upper receiver in an AR15 vise block and tighten the vise block in a bench vise.

    • 6

      Use an AR15 armorer's tool to remove the barrel nut at the base of the barrel. Remove the barrel from the receiver.

    Barrel Installation

    • 7

      Apply a coating of molybdenum disulfide grease to the barrel threads.

    • 8

      Insert the barrel into the upper receiver, guiding the alignment pin on the barrel into the slot on the receiver.

    • 9

      Tighten the barrel nut, with an AR15 armorer's tool attached to a torque wrench, to 30 foot-pounds of torque. Loosen and re-tighten to 30 foot-pounds of torque two more times. Now tighten once more with sufficient torque to turn the nut so one of the gas tube notches in the barrel nut aligns with the gas port in the receiver. Do not tighten to more than 80 foot-pounds of torque.

    • 10

      Insert the gas tube through one of the holes in the barrel slip ring, through the barrel nut notch and into the gas port in the upper receiver. Slide the other end of the gas tube into the front sight base and secure it by driving in the retaining roll pin.

    • 11

      Remove the upper receiver from the vise block. Reinstall the upper receiver on the lower receiver and secure it in place by replacing the front and rear take-down pins. Replace the handguards.