Finding the Right Length: Minimum Handguard Size to Cover the Gas System on an AR-15

When customizing an AR-15, one of the essential considerations is selecting the appropriate handguard length. Apart from aesthetic appeal, a handguards primary function is to provide a protective covering for the gas system, protecting the system itself, and you from the gas system as it heats up when the firearm is fired. In this article, we will explore the minimum length free-floating handguard required to completely cover the gas system on an AR-15. Understanding these measurements will help ensure a seamless fit and keep you from burns from an uncovered gas system.

Determining the Gas System Lengths

The gas system length in an AR-15 directly affects the minimum handguard size needed to fully cover the gas system. Let's examine the typical lengths for different gas systems, (note, these do not include the length of the gas block, just the exposed section of the gas tube.):

• Pistol-Length Gas Tube: Exposed gas tube length of approximately 4 inches.
• Carbine-Length Gas Tube: Exposed gas tube length of approximately 7 inches.
• Mid-Length Gas Tube: Exposed gas tube length of approximately 9 inches.
• Rifle-Length Gas Tube: Exposed gas tube length of approximately 12 inches.

Choosing the Correct Handguard Length

To achieve complete coverage of the gas system, it is crucial to select a free-floating handguard that extends just beyond the gas block and gas tube at a minimum. The formula for finding the correct minimum handguard length is quite simple, just add one inch to the exposed gas tube length to cover the entire gas tube and most low-profile gas blocks. Here are the corresponding minimum handguard lengths for each gas system:

1. Pistol-length gas system: For an AR-15 with a pistol-length gas system, a minimum handguard length of 5 inches is recommended. This ensures that the handguard fully encloses the gas system while providing enough room to grasp the fore-end of the firearm.
2. Carbine-length gas system: A carbine-length gas system requires a minimum handguard length of 8 inches to provide complete coverage. This measurement guarantees that the handguard extends beyond the gas block and gas tube, offering optimal protection for the gas system.
3. Mid-length gas system: To fully cover a mid-length gas system, it is recommended to choose a free-floating handguard with a minimum length of 10 inches. This ensures complete enclosure of the gas system while allowing room for additional accessories or attachments.
4. Rifle-length gas system: A handguard of 13 inches will cover the gas tube and gas block of a rifle length system.

Please note: the above assumes the use of a low-profile gas block of approximately 1 inch long. Longer gas blocks will require a longer handguard to be fully covered.

When customizing an AR-15, selecting the appropriate handguard length is crucial for achieving a seamless fit and complete coverage of the gas system. By referencing the gas system lengths and their corresponding minimum handguard lengths, you can ensure that you and your AR-15 are adequately protected while providing room for customization options. Always consult the manufacturer's specifications for the specific handguard you plan to use, as there may be slight variations in measurements for handguards.

The other consideration for handguard choice is the overall length of the barrel. A longer handguard provides more space for accessories and protects more of the barrel from damage; however, care must be taken to not overlap a free-float handguard and the muzzle device of your firearm. An overlap at the muzzle can both damage the handguard and potentially cause injury if grasping the handguard close to the muzzle.

Maximum handguard length also has a simple equation; The “maximum” length of handguard is your barrel length less approximately one inch. For Example, a 16-inch barrel will have a maximum handguard length of 15 inches. You can also round up or down slightly to avoid needing an extremely uncommon length for your handguard. A 13.9-inch barrel, for example, would technically need a 12.9-inch handguard, but 12.9 inches is not a common measurement for handguards. In this case, you could just a 13-inch handguard as that is a more common size and will still fit the barrel.

One consideration for Faxon Firearms is our unique, integral muzzle device barrels. These barrels have a legal length of 16 inches, but they have either a flash hider or muzzle brake built into the end of the barrel. For this reason, we generally recommend treating them as if they were a 14.5-inch barrel with a permanent muzzle device attached. With this in mind, we recommend a 13- or 13.5-inch handguard as a maximum.

Remember, the gas system is a critical component of the AR-15, and proper coverage and protection will contribute to the overall performance and longevity of your rifle. Not to mention the protection it offers you as the individual operating the firearm from burns from a hot gas tube or gas block!

(Note: The gas system and handguard lengths provided in this article are approximate measurements and may vary between manufacturers. Always refer to the specific manufacturer's specifications for accurate measurements.)

If you have any questions at all, or need help determining what length handguard you need for your next build, feel free to reach out to our customer service team! They are always happy to help and answer any questions that you may have. They can be reached via email at customerservice@faxonfirearms.com or via phone at 513-280-8861.