Installing Your STNGR USA Free-Float Handguard

Installing Your STNGR USA Free-Float Handguard

Posted by STNGR USA on Oct 23rd 2020

Your new free float STNGR handguard has arrived and you need to install it. We are here to help, with our step by step guide to removing your old handguard and installing your new free float STNGR handguard! It’s a simple process, but it requires a few tools and a little know-how to do correctly. We've got you covered!

Installing Your STNGR USA Free-Float Handguard 

First steps: What are the tools required for installation?

To install your new STNGR USA free-float handguard, you will need:

Moly Grease - A grease material for readying the threads for the barrel nut.

Blue Loctite - Loc-Tite is a locking compound that secures bolts and pins. For securing Allen bolts in this guide.

Roll Pin Punch Set - Specialized punches that will not warp roll pins when being installed and removed. For Removing Gas Block Roll Pins.

Armorers Wrench - A multi-tool every AR owner should own for maintenance and building rifles. For removing the previous barrel nut as well as removing the flash hider.

Mallet or Nylon Hammer - A hammer than deliver force without warping, chipping, or breaking small parts on your rifle. For tapping the gas block on and off as well as removing and installing the pins.

Vise - A standard bench vise is a must have when installing a handguard to hold the upper receiver steady.

Upper Vise Block - This wraps around the upper receiver and fits between the vise and upper. This protects the upper receiver from deformation and damage inside the vise.

AR Bench Block - A bench block designed to be a platform to build the upper receiver on. Is a great aid in installing the gas tube into the gas block.

Allen Key - A 5/32" Allen key is included to help remove the Allen bolts. A 3/32" Allen key will be needed to help you install the gas block.

Crowfoot Wrench - An included wrench (a 1 3/16" Crowfoot wrench with 1/2" drive) for installing the STNGR barrel nut. Hooks onto your Torque wrench.

Torque Wrench - Used to apply the necessary foot-pounds of torque to tighten the barrel nut down and make sure it's not going anywhere anytime soon.

Wheeler Torque Wrench Screwdriver - A Screwdriver torque wrench that allows you to apply the appropriate amount of foot-pounds torque to the set screws when installing the handguard.

Breaker Bar - Used to release tension in coordination with the crowfoot wrench. Allows you to season the threads.

Step-by-step Installation

We're going to be following along pretty closely with DocTacDad's video on upgrading his Ruger AR556 with installation of the 15" HWK M-LOK STNGR Handguard.


1. The first thing we are going to do is ensure the gun is unloaded. Clear the weapon and remove any live ammo or magazines.

2. Now separate the upper and lower receivers. You can set the lower aside, we won’t be using it today. The same goes for the BCG and the charging handle.

3. If you are upgrading an existing rifle you’ll need to remove your current handguards, which may require a handguard removal tool. Once the handguards are removed you can set them aside.

4. Attach your upper vise block to your upper receiver, and then to your vise. Tighten this down until it’s nice and snug in your vise.

5. We need to remove your muzzle device. Your armorer’s wrench should have a muzzle device removal tool, if not you may need a flats wrench and blue tape to remove your muzzle device. Regardless of how, go ahead and remove the muzzle device

Removing the Gas Block and Gas Tube

6. Now we have to remove your gas block. There are two types, gas blocks with front sight bases and low profile gas blocks. We’ll cover both.

    1. For an FSB gas block, you’ll need to remove the taper pins that secure the front sight base to the barrel. This might take some beating to get them out, but it must be done.
    2. If you have a low profile gas block all you need to do is use your Allen wrench to loosen the screws holding the block on. If those screws were applied with Loc-Tite apply heat to loosen them.
    3. You may need to carefully drive the gas block forward via nylon hammer or mallet. Once it’s loose it should slide forward and it can be removed.

7. With an FSB gas block, we need to remove the gas tube.

    1. You’ll need to remove the gas tube from the FSB with your #2 roll pin punch. You can then take the gas tube and install it into your low profile gas block. It’s easiest if you have a bench block but you can get by without one.
    2. With your bench block in place, you’ll need to align the gas tube with the large hole facing downwards into the low profile gas block. The small side holes in the gas tube need to align with the small holes in the gas block. Once it is properly aligned, use something such as a slave pin to keep everything aligned.
    3. Slowly insert a roll pin by hand as far as you can. Then drive the roll pin until it is flush with the gas block and holds the gas tube inside the gas block. It's pretty easy to press in and your roll pin punch will be able to accomplish this.

8. If you did not have a front sight base, you get to skip this step and you can just remove your gas block with the tube attached.

Removing your old barrel nut and installing a STNGR proprietary barrel nut

9. Grab your armorer’s wrench and remove the old barrel nut. The difficulty of this will vary, but shouldn’t be superbly difficult. Especially if it’s in a vise. Once the old barrel nut is removed you can then clean the threads and ensure they are ready for the next barrel nut.

10. Apply chrome moly grease onto the threads of the barrel nut. You can then hand tighten the barrel nut down. What’s cool about the STNGR barrel nut is that it does not need to be indexed and the gas tube will just go right over it.

11. Once the nut is tightened you’ll need to break out the torque wrench, the breaker bar, and included crowfoot wrench. Set the torque to 30-foot pounds and attach the crowfoot wrench to the torque wrench.

12. Torque the barrel nut down appropriately. Now we are going to use a breaker bar with the crowfoot wrench to loosen it once more. You can use your torque wrench for this but may damage the wrench’s internals. Breaker bars are a safer tool to use.

13. We are going to loosen and retighten the nut three times to season the threads. This is in the old Colt manual and ensures the barrel nut is going nowhere. On the final tightening, you can go over 30 ft pounds. 40 ft pounds is a good in-between, but 30 will still work. Max 60 ft.-lbs.

Installing the gas block

14. Now you need to apply a little lube to the gas block area. Just a thin layer. Take your gas block and slide it down to the barrel and align it properly with the gas port, and the upper receiver. You may need to use your mallet or nylon hammer to push the gas block downwards until it reaches the shoulder.

15. Once the gas block is installed, apply Loc-Tite to the gas block screws. Then tighten down the screws with your Allen key. Ensure the gas block is tight and does not move.

Installing your STNGR USA Handguard

16. Give everything a keep wipe down and grab that new, STNGR free float handguard.

17. Align the handguard properly and slide it over the barrel and gas block until it’s against the top of the receiver. Install the anti-slide plate and put a little blue Loc-Tite on the set screws. Using a torque wrench screwdriver install the set screws with 20 to 30 in-lbs of torque. Max 45 in-lbs.

18. That’s it, folks. Reinstall your muzzle device, and put your gun back together. Your handguard is installed and you are ready to go. The handguard has built-in anti-rotation points and it shouldn’t budge.

Final Thoughts


Installing a STNGR USA handguard is much easier than a traditional rail. Our proprietary barrel nut is second to none when it comes to ease of installation and you’ll never have to lap a barrel nut or ensure everything is indexed properly. With about 10 minutes worth of work, you have a new and improved handguard that’s lighter, more modular, and stronger than most rails out there on the market. Shoot us a message if you ever have any questions about install and we'll be happy to assist!