Mount a Light to Your AR-15 in Four Steps for Just $5.65

AR-15 handguard with rail mount light

The experts agree: Every basic defensive carbine requires three add-ons to be considered adequate for any task: A sling, a light, and some kind of optic.

Not everybody is financially able to deck out their AR-15 with these essentials, however. So, what’s a cash-strapped shooter to do? Simplify, of course.

For more on how to set-up an AR-15 on a budget, click here and here.

Realistically, you can get away without a sling for a home-defense gun. And with practice, iron sights can be more than adequate for duty and defense. But the one thing that you can’t approximate or do “half-way” is target identification; and for that, you need a white light.

So, what’s the cheapest way to get an effective light on your gun? The answer (as with many answers) lies with Magpul. Magpul, and a little bit of DIY handiwork, to be specific. We’re going to drill a couple of holes, do some fancy sanding, and attach a Magpul MOE polymer rail section (I used the 5 slots section for this post) to a set of ubiquitous standard plastic AR-15 handguards.

Let’s get started!

Step 1: Lay everything out

While simple, the double-heat shield forend design is actually pretty effective at dissipating heat, and the regularly spaced ridges allow a sure grip with gloves or bare hands. But those same grippy ridges present an issue when placing our MOE rail section on the handguard. (More on that later.)

We chose to place our light at the 1:00 position, on the right side of the handguard. With the stubby carbine-length forend, this places the light in a good position to be reached with the support hand. Personal preference will dictate which side you prefer.

Step 2: Get out the rotary tool and a drill

Holes drilled in an AR-15 handguard
Sand down the ridges and drills holes for the rail.

Once you’ve measured carefully to make sure your rail will go right where you want it, get out your high-speed rotary tool and a fine-grit sanding drum and polish down those pesky handguard ridges. You’re not removing very much material; a light touch goes a long way.

It’s important to do this so that the rail has as much bearing surface as possible on the handguard. It also helps move the light in closer to the gun. At this point, you’ll want to remove the heat shields from the handguard. They simply pop right out.

After the ridges and heat shields are gone, double-check the rail fit and then use the actual rail itself as a template to mark the holes for drilling. Dimple the center of the marks with a nail to help guide the drill bit, and cut two appropriately sized holes into the handguard.

Step 3: Bolt on the rail section

Magpul rail mounted to an AR-15 handguard
After the holes are drilled, simply bolt the rail section in place with the included hardware.

Deburr all plastic shavings from the holes and check to make sure that everything lines up. Once this is accomplished, orient the rail section so that the forward section is facing towards the muzzle end of the handguard. It’ll be easy to tell which end goes forward, because if you drilled your holes in the right places, it will over hang the front of the handguard slightly.

This is good, because you want your light as far forward as possible while still giving the bolts enough purchase on the handguard to remain secure.

Don’t get too crazy when tightening everything down. It’s possible to go so tight that you flex the body of the handguard, and then you’ll have a gap between the two halves when you put it all back together. The Magpul screws feature a thread locking compound that’s already been applied, so this will help quite a bit with retention.

Step 4: Trim the heat shield and reassemble

Underside of an AR-15 handguard
The underside of the handguard, showing the MOE backplates and trimmed heat shields.

Once you have the rail section bolted on, it’s time to trim the heat shields. Because the bolts stick down into the handguard slightly, they will keep the heat shields from snapping firmly back into place. A few minutes of cautious work with a set of tin snips or metal shears, and you’ll be ready to assemble everything and attach your light. Finished!

AR-15 handguard with rail mount light
The bolted-on rail is remarkably secure, and keeps the light tucked well into the rifle.

Peace of mind, for under $6

This method works best with smaller, pistol-style weapon lights. Many models are bright enough to serve on a long gun, and present a compact package as well. That being said, there’s nothing wrong with using a bigger light, if it’s what you’ve got handy. This rifle just so happens to be equipped with the versatile Streamlight TLR-1.

When you hear that bump in the night on the other end of the house and rush to investigate, there can be no second-guessing about who your target is, or isn’t. Tragically, mistaken-identity accidents do happen. Adding a quality weapon light to your home defense plan doesn’t cost a lot of money, and can go a long way towards preventing the unthinkable.

Which light or laser rides on your home defense carbine, and how do you have it mounted for quick activation? Let us know in the comments.


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Comments (6)

  1. Once, sometime ago, I designed and built a multi-device for home defense. It to had law enforcement applications. The device combined and enhanced directional microphone, connected to headphones, a 50,000 candlepower, flashlight, that would strobe, all tied in with a laser that was set, point-of-aim at 25 ft. It worked very well under test conditions. While it was generally agreed, even by some LEOs that I knew, that it was a good concept, it wasn’t practical for home defense or law enforcement. The general agreement being, that the ultra-bright flash and the strobe, may or may not, blind your opponent and would surely draw fire.

  2. Mini-Mag Lites, work well in a scope ring, if you’re not using optics on you rifle. Plus, at one time you could purchase a replacement end cap for the that has a coiled length of wire, terminating in a pressure switch that could be mounted near your trigger. If you are using optics and don’ have an acc. rail, several manufactures, at one time, offered a flashlight mount that clamped around you barrel. What would be better, but somewhat more expensive, would be an infa-red light and glasses. That way, your bright white light wouldn’t be a target for your intruder to shoot at. You could see him, clearly’ but, he could only guess at your position. But, then, if you are going that far, invest in night vision. either a scope or goggles.

    1. I agree with and use the mag-lite idea. I have 3 XL50 led mag lights and love them for their brightness and simplicity. Two of them I put 1″ scope rings on them (one is offset) and have them on my home defence weapons. The 12 gauge has one and the AR gets the offset one. The offset mount was $5 off Amazon. It also works as a great light for my Ruger SR22 .22lr pistol! Perfect light set up for the common man (or woman).

  3. Nice. Good article. Practical, and as long as you don’t have some deep-set need to have the ultimate in an M4 like the ones in Recoil Magazine, then you’re good to go.

    Another good trick for saving some bucks if you already have a rail or handgun mount, is to use a simple scope ring to hold a good flashlight. It won’t be a quick release or anything fancy, but it will hold the light firmly and do the job.

  4. If using a full drum who needs a flash light? Attach a sling place across your shoulder and your ready to rock and roll

    1. @Glock Guy

      No offense, but this sounds a bit like the famous spray and pray philosophy. Why worry about what or where the target is, just spray and you’re bound to hit something. Along with the critical task of providing positive target ID, a light also blinds and disorients your attacker.

      And if it’s being identified by your flashlight that worries you, remember Sun Zsu’s maxim, the attacker may choose the time of the battle, but the defender chooses the place. You know your home layout better than any intruder. Use that knowledge to position yourself so that when you hear that sound that is out of place, you light them up and then light them up.

      A light mount is a tactical advantage, and if you determine the situation isn’t right to use it, then simply don’t use it. but give yourself every advantage you can BEFORE the encounter.

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