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Brownells – Changing A Gas Block

In this detailed guide, you will gain comprehensive knowledge on how to change a gas block, brought to you by the experts at Brownells, Inc. Replacing the front sight housing gas block on an A2 style barrel and switching it with a modular one requires careful steps and particular tools, a process you’re about to become well-versed in. You’ll discover the utility of tools such as a roll pin punch, and you’ll learn how to maneuver the gas tube effectively, taking it out of your way or leaving it in situ while removing your front sight.

In addition, you will learn how to ensure your replaced gas block is secure and properly aligned. Careful checks to ensure a good, open gas port, and using a hex key to drive set screws ensures your firearm functions smoothly. By the end of this guide, you will know how to align your gas tube with a roll pin and have the know-how to test your action to make sure the bolt aligns perfectly with your newly placed gas tube.

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Table of Contents

Understanding the Front Sight Housing Gas Block

Definition of front sight housing gas block

Your AR15 relies on a suite of components for its operation, amongst which the front sight housing gas block plays a rather important role. The gas block in a firearm, as the name suggests, is a block that’s fitted onto the barrel of the firearm to house the ‘front sight’ – an element crucial for its aim and accuracy, and to ‘block’ and manage the flow of gases that are released when the gun is fired.

Importance of the gas block in an AR15

The significance of the gas block in an AR15 stems from its primary role in the rifle’s operating system. As your AR15 is fired, the propellant gases are funneled into the gas block via the barrel’s gas port. These gases drive the action of the bolt carrier group, extracting the spent cartridge case, and chambering a new round. The gas block thus propels and ensures the smooth functionality of your AR15.

Distinct features of an A2 style barrel’s gas block

The A2 style barrel’s gas block differs from others owing to its integrated front sight. Aside from acting as a conduit for the gas system, it also serves as a mount for the rifle’s front sight post. This dual function makes it a more complex piece of engineering, which can be a boon for those wanting a traditional, military-style look for their AR15, but a hindrance when looking towards modernization and adaptability of accessories.

Removal of the Existing Gas Block

Removal of the muzzle brake

The first step towards replacing your existing gas block is to remove the muzzle brake. As a component affixed to the muzzle of the AR15’s barrel, the muzzle brake needs to be disassembled first to ensure a seamless gas block removal process.

The role of roll pin punch in changing gas block

In the gas block changing process, a roll pin punch plays a key role. This tool is designed specifically for the removal of the gas tube pin, a necessary step to dislodge your AR15’s front sight housing gas block.

Steps in removing the gas tube pin

To remove the gas tube pin, align your roll punch with the pin and strike it using a hammer. This will drive the pin out, enabling the removal of the gas tube if necessary. The gas tube pin might be quite snug; assure that you apply consistent force when performing this step.

Option of leaving the gas tube in place

You may choose to leave your gas tube in place during the gas block removal process. This method calls for less manipulation of your firearm and can make the procedure moderately effortless, as you will not need to dislodge the gas tube.

Driving out cross pins with the use of cut point punch

An important facet of the gas block removal process involves driving out the cross pins of the front sight housing. This is typically done using a cut point punch. As you do this, be cautious to prevent the rounding out of the holes, as it may complicate the reinstallation process or cause issues with your replaceable gas block.

Avoidance of rounding out the holes

Minimizing damage is a crucial element in any firearm maintenance task. Ensure that you are not rounding out the holes during the removal of the cross pins to maintain the structural integrity of your AR15.

Handling the Gas Block Post-Removal

Procedure for sliding off the gas block

Once the cross pins are properly handled, the gas block should come off with relative ease. Simply slide it off the end of the barrel. Try to execute this step with caution so as not to inflict avoidable damage on the gas block or the barrel.

Simultaneous removal of the gas tube

While removing your gas block, keep in mind that the gas tube might come out at the same time. Taking note of its alignment and direction can prove beneficial during the later stages when you reinstall the gas tube.

Assessment of gas tube’s serviceability

In the process of gas block removal and replacement, it’s advisable to check whether your gas tube is still in serviceable condition. The gas tube plays an important role in the proper functioning of your AR15, and any damage or misalignments with it could potentially lead to malfunction.

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Checks and Preparations Prior to Gas Block Replacement

Checking the gas port for any obstructions or burrs

In preparation for the installation of your new gas block, inspect the gas port thoroughly. Look for any obstructions or burrs which might hinder proper gas flow. If found, remove these obstructions for the superior functionality of your firearm.

Reviewing the condition of the gas port in the barrel

Besides obstructions or burrs, inspect the overall condition of your gas port. Look for signs of excessive wear or damage. If you spot any, consider getting professional help to fix it before proceeding with the gas block replacement process.

Installation of handguard cap

If your new gas block requires the use of a handguard cap, this is the appropriate time to install it. Check the manufacturer’s instructions for specific details about the order and direction of the installation.

Insight Into the Modular Gas Block

Features of a modular gas block

As you replace your front sight housing gas block, one option you might consider is the modular gas block. These gas blocks are advanced, with user-friendly features such as an adjustable gas flow, sleek ergonomic designs, and a simplified installation process usually secured by set screws.

Advantages of using a modular gas block

The modular gas block is favorably lightweight, thus reducing the overall weight of the AR15. It also allows a more extensive range of customization, be it installing larger aftermarket handguards or preferring low profile designs. Notably, they may offer adjustable gas settings, enabling you to fine-tune your firearm’s recoil and performance.

Securing the modular gas block with set screws

Unlike traditional designs, securing the modular gas block does not require the use of taper pins, rather it uses set screws. This feature provides for a more uncomplicated installation and removal process.

Reinstallation of the Gas Tube

Proper alignment of the gas tube’s hole

When reinstalling the gas tube, ensure it is correctly oriented. Ensure that the gas tube hole is to the bottom, lined up for its designated duty of channeling gas from the fired cartridge into the gas block.

Securing the gas block on the gas tube

Once you’ve installed the gas tube, slide your new gas block over it, ensuring proper correlation for a secure fit. Ensuring proper alignment between the gas block and gas tube is vital for smooth operations of your AR15.

Ensuring a level surface

Before proceeding, make sure your gas block is aligned properly and there are level surfaces. The alignment of the gas block to the barrel is important. Any inaccuracies may cause malfunctions or affect the performance of your AR15.

Tightening Set Screws

Using an Allen Hex key for set screws

To secure the gas block properly in place, utilize an Allen Hex key to tighten the set screws. Ensure the screws are secure but avoid overtightening as it may damage the threads or the gas block itself.

The friction fit in the installation process

The friction fit gives you an indication of the gas block fitting snug onto the barrel. As you tighten the set screws using the Allen Hex key, the friction fit ensures the gas block is secured optimally on the barrel.

Achieving a secure position with set screws

Through correct application of set screws, you can achieve a secure position for the gas block. It’s crucial that the gas block remains unmoving under recoil, and the set screws play a vital role in ensuring this stability.

Aligning Gas Tube with Gas Tube Roll Pin

Procedure of running the gas tube forward

To correctly align the gas tube with the gas tube roll pin, you need to run the gas tube forward. This procedural step facilitates accurate placement and functional alignment.

Ensuring proper index of gas tube

Assure that the gas tube is indexed properly to avoid malfunctioning. Proper indexing sets up correct alignment with the bolt carrier group, ensuring the smooth operation of your AR15.

Removal and insertion direction for roll pin

When dealing with roll pins, it’s crucial to remember that they should be removed and inserted from the same direction. This practice retains the structural integrity of the pin’s hole and prevents unnecessary damage or wear.

Testing Post Installation Functions

Check action for bolt cycle alignment

After the installation process, it’s important to test your firearm’s action. Check whether the bolt cycles correctly and aligns with the gas tube. Any misalignment could potentially lead to a poor cycling of the bolt, affecting the overall performance of your AR15.

Testing if bolt and charging handle moves freely

Also, verify if the bolt and charging handle move freely without obstructions. Both should function smoothly. Any snagging or stalling can indicate an installation error or misalignment that needs to be addressed.

Cycle testing before actual use

Before actual usage of your AR15, carry out a few test cycles. This step doubles down as a safety measure and a performance check to ensure the correct operation of your firearm. It gives you confidence that your firearm is ready for usage, with necessary modifications incorporated.


Importance of correctly changing a gas block in a firearm

The process of changing a gas block in an AR15 is an essential skill for any firearm enthusiast. Having a clear understanding of this process not only ensures that your firearm operates efficiently but also saves you unnecessary visits to the gunsmith, providing more opportunities for customization.

Tips and tricks to ensure smooth transition

Remembering the small details, like avoiding rounding out of pin holes, remembering the removal and insertion directions, and careful alignment of components can ensure a smoother transition when changing your gas block. Always be patient and systematic in your approach. Rushed work can lead to unnecessary errors or even cause damage to your firearm.

Reminder of safety precautions and needed expertise for the task

Although the process for changing a gas block is straightforward, it is essential to remember that you are dealing with a complex and potentially dangerous weapon. Always adhere to strict safety measures when handling firearms and ensure you are competent and comfortable with the task at hand. Should you encounter any difficulties, don’t hesitate to seek professional help.

By following the guidelines outlined in this article, you should be able to successfully remove your existing gas block and replace it with a new one, thereby ensuring the continued optimal performance of your AR15.

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