Free Float Quad Rail Installation, Step-by-Step

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Last Updated on May 20, 2021.

Writer for Minuteman Review, handgun aficionado and artisan firearms reviewer. 

If you want to replace the standard mil-spec two-piece handguards, you have a wide variety of options. One of the most versatile is the free floating quad rail handguard.

Free Float Quad Rail Installation, Step-by-Step

However, you’ll need to know how to install a free-float quad rail, unless you want to pay for professional installation. Fortunately, installing a quad rail is relatively simple.


Free Float Quad Rail

Whether you’re building an AR-15 or modifying a factory-assembled rifle, a free floating quad rail handguard offers numerous advantages over the traditional two-piece mil-spec handguards. The first is that the free floating handguard can improve inherent accuracy by promoting uniformity in barrel vibrations, because it doesn’t touch the barrel. 

Another is that you can fully accessorize your rifle by using a quad rail interface, attaching different sighting systems, vertical or horizontal foregrips, flashlights, laser aiming modules, and bipods. 

You may be asking, “What is a quad rail?” The MIL-STD-1913 Picatinny rail is a popular mounting system for small arms, standardized in 1995. You can attach accessories directly to the rail, providing nearly endless customizability.

The handguard features four rails in the quad configuration — one at 12 o’clock, 6 o’clock, 9 o’clock, and 3 o’clock. 

Installing a free floating handguard is not an overly complicated task. If you have the correct tools and follow instructions carefully, it’s relatively simple.


Installation

Before removing your existing handguards or disassembling the rifle, you should clear it, ensuring it is unloaded and safe to handle.

While holding the rifle in your dominant hand by the pistol grip, with the muzzle pointed in a safe direction, depress the magazine catch and remove the magazine. Always remove the magazine first

Retract the charging handle and inspect the chamber. Ideally, you should verify the status of the chamber both visually and by feel—i.e., insert your little finger into the chamber to verify that it is unloaded. Press the trigger to drop the hammer. 

If you’ve googled “How to install free float quad rail on AR-15?” you’ll find that the process is not insurmountable. You’ll need to perform the following actions:

Remove the factory handguards

If your rifle is equipped with traditional circular two-piece handguards, you’ll need to remove these. You can use a handguard removal tool to perform this action, which compresses the delta ring to detach the handguards from the rear. This can save you time and effort. 

Separate the upper and lower receivers

Using a pin punch, cartridge tip, or another tool, press the rear takedown pin in and pull it out. Break the gun open. Retract the charging handle and remove the bolt carrier group from the upper receiver. Pull out the front takedown pin and separate the two receivers.

This can simplify the removal process, especially if you have a vice.

Remove the muzzle device

Unscrew the flash suppressor/flash hider from the muzzle using a wrench. Ensure that the muzzle device is not pinned to the barrel to meet the legal length requirement. 

Remove gas block/sight pins

If your rifle has a mil-spec gas block/front sight, you’ll need to remove it to slide the free floating handguard over the barrel. However, if your rifle is equipped with a low-profile gas block, this step may not be necessary.

A sight block can be useful but isn’t strictly necessary. You should use a punch to drive the two barrel pins out. These pins keep the gas block/sight assembly attached to the barrel.

Remove the gas tube retaining pin

Once you’ve removed the pins that hold the gas block in place, you can drive out the roll pin that retains the gas tube in place.

Remove gas block/sight assembly

After driving out the three pins, you can remove the barrel’s gas block and sight assembly. You can expect the gas block to offer resistance, so you may need to help it. If you have a nylon or rubber mallet, a wooden block, or another object that’s softer than the steel, you can use that to encourage it.

Remove delta ring/barrel nut assembly

Place the upper receiver in a vice using vice blocks to avoid damaging the aluminum or marring the finish. Using an armorer’s tool, loosen and remove the delta ring and barrel nut. Clean and inspect the upper receiver threads.

Replace barrel nut

If your quad rail handguard comes with its own barrel nut, you’ll need to install this. Unscrew the barrel nut from the handguards and slide it over the barrel with the lock ring facing toward the upper receiver. Tighten it on the upper receiver using an armorer’s wrench.

Torque and loosen

Using a torque wrench, tighten the barrel nut using 30 ft-lbs of torque. Remove the torque wrench and loosen the barrel nut with an armorer’s wrench. Tighten the barrel nut again to 30 ft-lbs of torque and loosen again. Perform this action a total of three times to ensure that the threads are perfectly mated, verifying alignment throughout

Reinstall the gas tube 

When you retighten the barrel nut, ensure that the hole in the upper receiver for the gas tube is aligned with the hole in the barrel nut.

Loosen the lock ring

Loosen the lock ring and thread the quad rail handguard onto the barrel nut.

Measure the quad rail handguard

You can use a level to ensure that the handguard’s top rail is correctly aligned with the top of the upper receiver. This alignment is critical, especially if you intend to use the handguard as a mounting platform for sighting systems.

Reassemble

Your new free floating quad rail handguard is installed. Now reassemble the rifle by inserting the bolt carrier group into the upper receiver and joining the upper and lower together. If you’re reinstalling the muzzle device, always ensure that the vents are facing the correct direction. If you’re using a muzzle brake, the exhaust ports are typically lateral. However, recoil compensators typically exhaust gases vertically. 


Tools and Organization

For precision shooting and additional accessories, the free floating quad rail handguard affords increased flexibility in comparison with the traditional mil-spec handguards. As you learn how to install a free float quad rail on an AR-15, you’ll see how vast the market for accessories, upgrades, and other equipment can be. 

Whether you’re building or modifying your rifle, you should invest in the necessary tools for detail stripping and parts replacement. These include an armorer’s tool, torque wrench, set of punches, a hammer, a mallet or wooden block, a bench vice, and a set of vice blocks.

You should also have a thread locking compound for applying to screws and threads. This will ensure that threaded parts don’t loosen as readily over time due to heat, vibration, or shock. 

Don’t neglect adequate space for working. A sturdy workbench or table is highly recommended. 

A set of drawers, bins, or trays to keep spare parts, small tools, and other supplies organized and handy is also a good idea.


Consider Becoming a Hobbyist

Once you’ve learned to install a different handguard, the sky’s the limit. This can be an excellent introduction to the hobbyist side of AR-15 assembling.