How to Barrel Mount a Streamlight Protac HL-X Weapon Light

How to barrel mount a Streamlight Protac HL-X weapon mounted light.

Barrel mounted Streamlight Protac HL-X
My Barrel-Mounted Streamlight Protac HL-X

I recently decided that I needed to put a white light on my AR 15 style rifle. I keep my AR-15 ready to go by my bed, ready to defend my family should it become necessary. The end result was a barrel mounted Streamlight Protac HL-X.

I also realize that if I would need to use a firearm for self defense, it will likely be at night, or perhaps late in the day when natural light will be at a minimum. I have had several handguns staged around the house with tactical flashlights next to them for years.

You need a white light mounted to your AR-15

I have been completely missing the fact that if I go to the rifle, I am going to need both hands on the rifle and will not be able to also hold a Streamlight ProTac HL in order to identify my target! This is a pretty big problem, so I immediately realized I needed to rectify this oversight.

So I began my research into how I was going to mount a tactical weapon light to my AR 15 and what kind of light I should purchase. Fortunately, my wife places security as a very high priority in our home. So she basically told me to immediately purchase any light that I felt would be necessary to mount on our home defense weapon! Yes, that is correct, my lovely wife encourages me to invest in guns and ammo and to take training classes!

Streamlight Protac HL-X Rail Mount Weapon Light

As I began my research on the Internet, YouTube, and gun magazines, the Streamlight HL-X kept popping up as a powerful yet relatively affordable weapon light. Since I am already a huge fan of Streamlight handheld lights, I was intrigued and began to look for reviews on this weapon light.

Streamlight Protac HL-X Weapon Light

See my article on the Best Tactical LED Flashlight Review.

Why I chose the Streamlight Protac HL-X for my AR-15

Here are the main features that ultimately help me choose this light:

  • Dual Fuel. This light works with one 18650 or 2 CR123A batteries. I already have a bunch of high quality Streamlight rechargeable batteries and chargers of both sizes.
  • 1000 Lumens. I love lumens, the more, the better on a weapon light! This is super bright for excellent identification and potential blinding of an attacker.
  • It is a Streamlight. As I mentioned earlier, I have many Streamlight tactical flashlights and I love them all. Super reliable and durable.
  • Comes with mounting accessories. Includes the remote pressure switch and mounting hardware for most applications, although I had to buy a barrel mounted Picatinny rail for my unusual situation.


I decided that it was going to be the light that I would purchase. The next thing I had to figure out was how to mount it to my AR forend (hand guard). So far, the only things I have mounted to my AR’s have been red dot sights and a pair of Magpul pop-up sights.

Problems mounting the light on my AR-15

I ran into a couple of problems right away with my particular AR 15.

  1. The hand guard ends a long way from the muzzle.
  2. The mounting systems on the hand guard was not one of the popular types.

My AR is made by Stag Arms and has a Diamond Head 7 inch forearm mounted on it which I love very much. As I have little experience so far with the different types of forend mounting, I assumed there were only two types of systems for attaching accessories to hand guards or forends: KeyMod and M-lok.

Mine did not look exactly like either one, but I thought that what I had was compatible with M-lok components so I ordered an M-lok accessory Picatinny rail to mount to my forend, which I would then use to mount the Streamlight HL-X which comes with a fixed mount for a Picatinny rail.

Turns out, the mounting system on the Diamond Head is VRS (Versa Rail System), which I had never heard of before. I did research on the Internet and discovered that this system is not very easy to find and also very expensive. I decided to find another way.

I ended up with the idea of mounting the Streamlight HL-X directly to the barrel with an $12 barrel mount!

Inexpensive Barrel Mount For Streamlight Protac HL-X
Barrel Mounted Picatinny Rail Holding My New Streamlight Protac HL-X Weapon Light

My research determined that the ideal location for a white light on a rifle is close to the end of the barrel, but not quite as far forward as the end of the barrel. The reasons for this is that if the light was further back then there would be a shadow when using the light caused by the barrel.


Conversely, if the light is lined up with the end of the barrel, the light would be subject to carbon fouling every time the rifle was fired. This would require that the light be cleaned often.

Other mounting options

There are several other ways I could have gone that were more involved and much more expensive. The simple option would be to replace the Diamond Head hand guard with a longer one, and then attaching the light at the front end. Not only would this cost $100-$300, it would also require some disassembly and reassembly. I was looking for a quick fix here, not a weekend project!

I could have purchased a set of VRS add-on rails, at about $60, but the location of the flashlight would be much further back on the rifle, creating a shadow in the light. This would be acceptable, but not really wanted the light to be in the ideal location relative to the end of the barrel.

Conclusion

I am very happy with the final result and the Streamlight Pro-tac HL-X is an excellent light. It is super bright and the pressure mounted switch works flawlessly and is mounted in a natural position just under my thumb when I grip the rifle.

Please comment below if you have any other suggestions or experiences with tricky weapon light mounting!

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