AR-15 Handguard change — Long Island Tactical Training

By John Diana

A year and a half ago - after much deliberation - I purchased my first AR 15 from a gun store in Huntington. You must know that I was and to a degree, I still am, a strong Mini-14 supporter. But, over time the "Black Rifle" appeal became too great and the credit card came out. My new Sig Sauer M400 in 5.56x45 was awesome and I could not be happier.

As time went by and I shot my AR more, I began to look at it with more of a critical eye. In finally removing my rose-colored glasses, I began to notice that the hand guard was quite wide (for my hand) and I could not get a good grip on the forend. In addition, the M400 has a large, steel gas block with an incorporated Picatinny rail, which weighs a ton and makes the front of the rifle feel "front heavy." Lastly, the sight radius is only 14 inches. That's ok if your shooting a Winchester 94 Trapper with a 16" barrel and open buck-horn sights, but in a rifle that can shoot to 200 yards, without breaking a sweat with iron sights, 14 inches is minimal. Now, to be honest, many times an optic is mounted to allow accurate placement and target identification out to 400 yards, the MBUS are simply back-up. But in my particular P.O.U. - Philosophy of Use - this rifle is set up for 0 - 200 yard engagement.

I therefore decided to research my options. It soon became obvious that the hand guard, gas block, barrel nut and gas tube would have to go, but what to replace them with was the question.

I decided upon a 15" hand guard from Bravo Company (BCM), known as the KMR. It is an aluminum/magnesium alloy which is very strong and light, only 5.9 oz. It is also thin, I can get my hand comfortably around 3/4 of the guard. Now to use this hand guard, I would need to replace the stock gas block with a lightweight aluminum, Low-profile (0.75") gas block which I purchased from Ballistic Advantage. I would also need to remove the current barrel nut and replace it with a proprietary barrel nut from Ballistic Advantage.

Since I am changing the gas block, I decided to change the stainless-steel gas tube to a Melanite-coated gas tube, also from Ballistic Advantage.

The project began with a struggle to remove the two tapered pins which secured the gas block to the barrel, they must be removed left to right. In hindsight, an Armorer's block could have made this task a bit easier. Once out, the fun really increased in trying to remove the factory pressed-on gas block, which required heavy hammering to remove. Yes, I tried soaking it in Liquid Wrench overnight along with heating it with a blow-dryer for two minutes - nothing except a strong hammer and an equally strong desire to get this thing off before midnight worked.

Now, with the gas block, the stock barrel nut, the Delta Ring, the gas tube and the hand guards removed, I was able to begin the rebuilding project.
I first, attached the new gas tube to the new gas block by tapping-in the pin. I next placed the new proprietary BCM barrel nut, "seasoned the threads" four times and set the final torque to 45 ft/lbs.

I called Ballistic Advantage concerning the torque for the Gas-Block screws. They stated, "make them hand-tight and then a little more." That answer did not make me feel comfortable. If the Gas Block loosens during function - proper function will cease.

I took it upon myself to dimple the barrel in order to provide a concavity for the screw tips to engage. I also used Blue Locktite and torque the screws to 12 inch/lbs - now I felt better!

The BCM KMR hand guard is a tight fit, to say the least. In order to slide it over the barrel nut you need to heat the metal with a hair blower for at least 60-90 seconds. This achieved 90% seating, I reheated the metal and with a wood block and a rubber mallet, I seated the hand guard completely. I then installed the two-hand guard locking screws, applying the provided Blue Locktite. The last step was replacing the front MBUS sight and placing a KeyMod front sling attachment.

Wow! What a beautiful modification I did 😍!

The "front heaviness" feel was gone, the rifle felt far nimbler. I could wrap my left hand around the hand guard in a secure fashion and the sight radius improved from a poor 14" to a full 20".

Next is to get it to the range, test it and sight it in!

All in all, it is comforting and rewarding to know that one can work and improve his AR with a minimal - but required - number of tools. The AR platform is truly a genius design, it is no wonder that it has lasted 50+ years in the military and has become "America's Gun."