Weapon-Mounted Lights – A Beginner’s Guide

Weapon-mounted lights, or WMLs, are a big industry these days. For way too long, only Surefire and Streamlight dominated the market. Now we have Modlite, Cloud Defensive, Inforce, and some I’m surely missing—all producing well-made weapon-mounted lights. When we start talking about WMLs, the conversation can quickly get confusing. Numbers, weird words, and more plague the conversations.

New shooters looking to outfit their handgun, rifle, or shotgun might be somewhat confused by all these terms and numbers being tossed around. Hell, experienced shooters might be surprised at what they don’t know.

Streamlight Protac HL-X tactical flashlight
Pretty Scary sight to find yourself on the wrong side of.

I never knew how much I didn’t know about weapon-mounted lights until I started doing heavy research into the realm. The complexity of lights fascinated me, and I want to share what I’ve learned with you.

My goal is to hopefully educate you and make it easy to pick out a bright, easy-to-use, and reliable WML.

What’s the Purpose of A Weapon-Mounted Light?

Weapon-mounted lights have now become a standard when it comes to outfitting a weapon for serious defensive use. This includes military and police dudes, home defenders, and concealed carriers. Lights are getting smaller and more potent on the reg.

Floodlight PHLster holster accommodates even unusual guns like the CZ P09
Some lights work well for concealed carry, and the Phlster Floodlight helps there too.

Which leads us to ask what the purpose of a WML is?

See your Target, Duh

I know the answer is obvious, but follow me here. It’s good to define terms and mission sets for our gear. If a light is made to see your target, it’s likely dark, right?

Well, duh, but is it foggy and dark? What if it’s raining and dark? Ooh, what if you’ve fired your gun a metric sh!t ton inside a building, and now the choking smoke of burning gun powder is filling the air?

Cloud Defensive REIN weapon mounted light
It’s a Bit long…

Can your light penetrate these barriers and allow you to identify a threat? Do you potentially need it to?

This is why it’s good to define terms and establish a baseline for performance. This is also why that 29 dollar Amazon light kind of sucks all around.

There is a second purpose to using a weapon-mounted light that should be discussed, and that’s

They Keep Your Target from Seeing You

A good bright white light will prevent a bad guy from easily seeing you. Sure, they may see your light, but the discomfort of the light will most certainly cause a bad guy to stop, stall, and have a shifted OODA loop.

A powerful weapon-mounted light allows you to disorient and blind a potential threat. You can cause real pain with a powerful light: the more power, the more pain.

Another serious consideration is what happens when a potential threat is toting their own light? If your light is more powerful than theirs, it can overcome their light and allow you to see the danger as if their light isn’t even present.

If the potential threat’s light is more powerful than yours, then he’ll see you, and you won’t see him.

Other lights create what’s called a photonic barrier. This barrier could be the high beams of a car at a checkpoint in Afghanistan, a streetlight, a bad guy with a WML, or just a dude wandering around with a flashlight at the wrong time in the wrong place.

photonic barrier created by flashlight
Photonic Barrier created by a Flashlight attached to an Ivan.
photonic barrier defeated by Cloud Defensive REIN
Photonic Barrier easily defeated by the Cloud Defensive Rein.

My goal isn’t to dive into tactics when using light but to establish the mission of a weapon-mounted light before we dive into the minutia of weapon-mounted lights.

So What Kind of Weapon-Mounted Light Do I need?

Good question, but it’s not an easy one to answer. Weapon-mounted lights are like any other tool you strap to a gun. It depends on the weapon’s capabilities and the user’s mission set.

Think of it like an optic. A 7-35X Nightforce ATACR kicks ass as a scope, but is it the best option for every task out there?

Nah, man, sometimes you need a 7-35X optic, and other times you need a Trijicon RMR. Use, weapon, and mission will drive your selection.

Cloud Defensive REIN weapon mounted light review.
Cloud Defensive REIN weapon mounted light on a Scorpion Bullpup.

I can’t tell you the exact light you need, but I can tell you the light you don’t want. Unless you are outfitting an Airsoft or BB gun, I would avoid those aforementioned Amazon 30 dollar lights.

I don’t just want to tell you to buy XYZ light because I say it’s okay. I want you to have the tools to choose your own light for your own mission.

(Although at the very end, I’ll drop a few of my favorite lights by purpose.)

Beyond Marketing

Oh man, 1,000 lumens sounds excellent! It is, but what does that mean? Is lumens the end-all, be-all for choosing a weapon light? Nope, but it’s an important consideration.

Let’s talk terms.

Lumens and Candela

Lumens is the measure of the total amount of light emitted by a device. Candela is the amount of light emitted in a particular direction. A thousand lumens of light backed by hardly any candela results in a very bright white light that has no real range to it. Lumens do not calculate the spread of the light emitted by a device.

Streamlight ProTac Rail Mount 1 weapon light beam, indoors

When it comes to weapon-mounted lights, it’s simple. Lumens are how brightly a light shines, and candela is how far that light travels. When lumens are focused correctly, you get a high candela, and a high lumen count paired with high candela results in a powerful light.

Candela and lumens have some give and take to it. A light with higher candela may have a low lumen count but will outshine a light with a high lumen count but low candela count.

On and On

You’ll want to focus more on a high candela count when you are looking for a weapon-mounted light that will be used outdoors or will need to overcome fog, rain, smoke, and photonic barriers. High candela lights are perfect for duty rifles.

The Cloud Defensive Rein packs 60k candela and 1,400 lumens which makes it a fantastic duty rifle light. It casts a powerful beam that cuts through various barriers, including photonic barriers, and gives an effective range that’s best suited by a rifle.

If you need a light for a home defense role where the light will be used indoors, then a higher candela count isn’t necessary. It’s not a bad thing by any means, but high candela and high lumen lights are often full-sized rifle lights that can be on the heavier side.

10-inch gong illuminated by Cloud Defensive REIN at 100 yards in the dark.
See how well this 10-inch gong is illuminated with light from REIN at 100 yards?

You may want a smaller and lighter-weight light for home defense, and that means a sacrifice of lumens and candela. That’s likely not going to be a big deal since fog, rain, and smoke are not situations you are likely to encounter. When your illumination range is 15 yards max, 1,000 lumens and 10,000 candelas are entirely acceptable. Heck, even 500 lumens and 5,000 candela isn’t a bad option for close-range use.

Examine the purpose of your light, and then start looking at the lumens and candela they offer.

Throw and Spill

Throw is the range in which the light is efficient. The throw of your beam is a measure of how far the light cuts through the darkness. Throw is all about candela, and the higher the candela, the further the light can reach.

Spill is how wide a beam is and how the light spreads across distance. Different beams are designed for various purposes. Some beams are all about the spill, and others all about throw. Spill and Throw share an inverse relationship with each other.

Cloud Defensive REIN illuminating a building at 100 yards.
I am impressed with the performance of the Cloud Defensive REIN. at 100 yards the WML easily lights up this building. INSIDE and out.

The more spill a light has, the less throw it has. Spill is perfect for close-range use. A wide beam fills up a room and would be a better option for home defense. If you are seeking a home defense light, then spill is important to consider. The wide beam fills a room and makes it hard to hide.

Most pistol and shotgun lights will prioritize spill over throw because of the weapon’s limitations. Other modern long gun lights like the TL RM1 and RM2 series are designed for home defense and also prioritize spill over throw.

weapon-mounted light Streamlight TLR1-HL
Handgun lights often have a lot of spill and less throw. In this image: Streamlight TLR-1 HL. Photo Credit PMM

A light with a long throw will illuminate targets at longer ranges. The Cloud Defensive OWL, for example, has an excellent degree of throw and has an effective range measured in the hundreds of yards. That same concentrated beam doesn’t fill a room like a light with a high degree of spread.


Temperature is not necessarily the heat you feel from the beam but the color it produces. There are cool and warm lights. Warm lights present a yellowish beam. Cool beams have a blueish tint to them.

weapon light use: direct lighting
Weapon Light In action!

This is more than aesthetics. Warm beams tend to penetrate all those barriers we keep mentioning a bit better, including photonic barriers. They also tend to show color better and more accurately than cool beams. They make it easier to pick out camouflaged people and to see important descriptors.

Cool beams tend to be brighter—much brighter with more intensity. They can flatten colors, but if you need the most brilliant light possible, a cool beam does it.

External Features

So far, all we’ve talked about is the internal effects of beams of light. They don’t tell the whole story, though, and you’ll also have to examine the external features of a light when choosing one. While we would all love the power of a Surefire Hellfighter, it’s not a practical light for my Glock 19.

Size and Weight

How big is the light, and how much does it weigh? Does a powerful, full-sized Modlite make a lot of sense on a Scorpion pistol? Hell, good luck finding the room to mount it and maintain decent ergonomics. Is an OWL appropriate for a Mossberg Shockwave? Again, not really.

Tiny little lights.

An examination of the weapon-mounted lights’ size and weight in comparison to the firearm you intend to mount it on is a must. Trying to mount a Surefire Uboat on a Subcompact pistol makes as much sense as squeezing your butt cheeks after you fart.

Length, diameter, and weight all need to be considered.


As far as weapon-mounted light controls go, there are a few different options that are often mandated by the design and intention of the weapon light. There are push-button tail caps, switches, and pressure switches.

Streamlight ProTac HLX - rail mount pressure switch
See how the pressure switch allows for easy access to activate the light.

In most cases, lights on rifles work best with a pressure switch. A pressure switch allows you to mount the light as far forward as possible and still maintain your ability to control the light. On a short rifle or shotgun’s pump, a clickable tail cap makes more sense.

Streamlight Protact HL-X components
Here is an example of a pressure switch with a Streamlight rifle light.

Switches dominate handgun weapon lights. Handgun lights on rifles can be used effectively, but you’ll either deal with a lot of barrel shadow or be regulated to a short rifle or shotgun. Some handgun lights, aka the Streamlight TLR-1, can be converted to use a pressure switch if you so choose.


Constant, momentary, and strobe are the typical modes weapon-mounted lights offer.

Constant is precisely as it sounds. The light stays on and turns off with a single input. Constant is for long-term search and assess situations and to control a threat.

The TLR-7A is a new entry in the Streamlight TLR series mounted to Taurus subcompact.

Momentary is when the light comes on for a moment and when the input is released, the light shuts off automatically. Momentary mode allows you to search or shine a subject then switch off to help keep a lower profile.

Strobe is party time. You flip it to strobe to distract and disorient a bad guy. It flashes on and off by itself.

Light it Up

Weapon-Mounted Lights are a must-have for serious use rifles. Home defense and duty weapons are especially well served by them. If you’re carrying a full-sized or compact handgun, then you have no excuse not to bring a light, especially when the Phlster Floodlight exists.

Weapon-mounted lights make a whole lot of sense.

We are living in an age where lights are getting better and better. Before you start shopping for a potentially expensive investment, it’s wise to approach it with a little knowledge on the subject. I hope the last 2k words and some change have given you a better idea of how to choose a weapon-mounted light to best suit your needs.


Travis Pike is a former Marine Machine Gunner and a lifelong firearms enthusiast. Now that his days of working a 240B like Charlie Parker on the sax are over he's a regular guy who likes to shoot, write, and find ways to combine the two. He holds an NRA certification as a Basic Pistol Instructor and is probably most likely the world's Okayest firearm instructor. He is a simplicisist when it comes to talking about himself in the 3rd person and a self-professed tactical hipster. Hit him up on Instagram, @travis.l.pike, with story ideas.

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