Illumination is key for proper target identification, making weapon lights some of the most critical accessories you can add to your rifle, after optics of course. And as far as quality weapon lights go, SureFire has some of the finest options the industry has to offer.
SureFire has long been one of the top brands in the firearm industry, renowned for crafting a wide range of top-tier rifle and pistol accessories, which, of course, include weapon lights. Looking at their rifle lights, they offer a plethora of unique models, but their M640 and M340 series are consistently some of their most popular.
In all truth and sincerity, you can’t go wrong with either one but depending on the size of your rifle, as well as how you use it, it’s critical to recognize that each light offers its own set of advantages. If you’re new to the game, weapon lights can be deceptively complex at times, but below, we’re looking at both of SureFire’s top rifle lights to narrow down the best choice for you.
SureFire: The Industry Standard
SureFire, as mentioned above, is one of the premier manufacturers of weapon lights, among other accessories, and their reputation often precedes them—for decades, they’ve been creating some of the industry’s finest weapon lights and lasers.
We cover this in our SureFire Brand Review, but before becoming the company we all know and love today, SureFire originally started out as a company called Laser Products. During this time, they worked on developing light and laser systems for various rifles and pistols of the time, and it wouldn’t be until 2001 that they would rebrand themselves as SureFire LLC. Since then, they’ve continued to develop a slew of specialized accessories for both rifles and pistols, with their rifle weapon lights being widely regarded by many enthusiasts as the industry standard.
SureFire Scout Light Overview
As far as cool vs. functional AR-15 accessories go, weapon lights fit into both categories with ease, and when looking at SureFire in particular, a lot of the renown that surrounds their rifle lights stems from their inherent quality. For starters, most, if not all, of SureFire’s products are made in the U.S. with premium components, and they also have extremely strict quality control measures to ensure that everything they send out is ready for everything from recreational to professional use. As such, their lights are designed to take a beating and keep working.
Constructed around a durable aluminum housing, SureFire Scout Lights are engineered to be light and tough, with both options being more-than-capable of seeing use in harsh conditions. From the factory, they come outfitted with specialized O-ring seals, making them dust proof and waterproof to IPX7 standards. Plus, its mil-spec hard anodized finish makes it resistant to abrasion and provides some extra protection against corrosion. The head units get the same treatment too, as they come standard with the same features, as well as a tempered glass lens.
SureFire Scout Light Modularity
Both the M640 and M340 Scout Lights are compatible with a plethora of tail caps. Depending on the tail cap model you add to your light, you can greatly increase its utility. Standard scout lights come equipped with the standard tailcap, one that comes with a basic push button to turn the light on and off. While not bad by any means, it isn’t the most conducive for fast activation since you need to let go of the rifle with your off hand to turn the light on. This is where SureFire’s replacement tailcaps come into play.
Their replacement tailcap often comes paired with either their SR07 or ST07 tape switches, which give you access to activate the light when needed—and when using a C-clamp or Costa style grip, you can activate your light just by shifting your thumb position. Finally, it’s relatively common knowledge that tape switch wires, and the switches themselves, can fail given enough time and harsh use. So, even though SureFire’s tape switches are designed to last a long time, it’s still something to be aware of. The last thing you want is your light to fail on you in the field, and you can easily rectify this with SureFire’s Dual Switch tailcap, as it has both a tape switch port and a push button for easy activation.
At the end of the day, SureFire’s Scout light options can be easily adapted and modified to best suit your own personal needs and preferences. So, regardless of how you plan to use your rifle, you can easily tailor a Scout light to fit any use case. That said, if you want a more in-depth look at how different light control setups work, you should check out our guide, “Comparing AR-15 Light Controls”.
SureFire M640: Power and Range
The SureFire M640 is one of the most popular full-size weapon lights around, and it’s also among the more powerful weapon lights available too. Just like many of SureFire’s other weapon light offerings, M640 series lights are available in multiple configurations, the most common of which being the M640DF, M640U, and the M640V.
M640DF Scout Light Pro
The M640DF Scout Light Pro is one of SureFire’s Dual Fuel weapon lights, meaning it can be powered by either an 18650 or two CR123A batteries. This allows for greater flexibility when swapping out your batteries, and, if you have other lights or optics that use CR123As, you don’t need to stress about always having multiple battery types on standby. However, it’s important to remember that the power output of your light depends on the type of battery you use.
Currently, the M640DF is available in two configurations that each have different lumen outputs and beam intensities. The standard M640DF can project either a 1500 or 1200 lumen white light projection with a peak beam intensity of either 16,000 or 12,800 candela, and a total run time of 1.5 or 1.25 hours when using 18650s and CR123As, respectively. As such, this light can throw light out to as far as 220 to 250 meters away, but since it has a more moderate light projection, it also does a respectable job of illuminating your surrounding area when active. In contrast, the M640DF Turbo can project either a 700 or 600 lumen beam of white light with a peak intensity of 100,000 or 90,000 candela. Despite its lower weaker lumen output, it has a far more concentrated beam, making it capable of illuminating targets as far as 600+ meters away.
M640U
The M640U is another notable Scout Light offered by SureFire. Functionally, it’s quite like the M640DF, however it differs in that it’s only compatible with CR123A batteries. Additionally, it projects a 1000-Lumen white light projection, with a peak beam intensity of 11,300 candela. Still, it’s capable of throwing light out to as far as 213 meters, making it a well-rounded weapon light that’s viable for illuminating targets at both close- and medium-distances. Plus, it offers up to 1.25 hours of constant run time, so you won’t need to worry about running down your batteries so long as you use your light sparingly.
M640V
One of the more unique options in the M640 lineup is the M640V Infrared Scout Light. With the ‘V’ standing for ‘Vampire’, it’s the only M640 Scout Light that’s capable of functioning as both standard weapon light and as an IR illuminator. Using CR123A batteries, it can project a 350-lumen beam of white light, with a peak intensity of 11,500 candela. So, although its white light output is a fair bit weaker than the other lights mentioned thus far, it can still throw light out to 214 meters with no problems, and it offers up to 2.5 hours of constant illumination. That said, its white light capabilities aren’t where this light truly shines.
As mentioned, the M640V can switch between a visible spectrum and IR mode. And in its IR mode, it projects a 120 mW (860 nm) beam of IR light that’s only visible under NODs. As such, if you’re building your rifle for dedicated nighttime applications, you can use the M640V to effectively illuminate targets without giving your position away, making it one of the top light options for nighttime hunting and duty applications. Plus, in its IR mode, it can run for 16.75 hours before the batteries die—so if you’re using it as a dedicated IR illuminator, you won’t have to change your batteries for a long time.
SureFire M340: Compact Power
Moving on to SureFire’s other popular Scout Light—the M340 series is essentially just a more compact version of the M640. It boasts the same rugged construction, just in a smaller overall package, making it ideal for compact rifle builds, or for those simply looking to minimize their setup’s final weight. That said, just like the M640 Scout Light series, there are multiple variants of the M340 series to choose from as well: the M340DF, M340C, and the M340V.
M340DF
The Surefire M340DF Mini Scout Light Turbo is a compact weapon light that, much like the M640DF, can use two different types of batteries. Using either an 18350 or one CR123A battery, the M340DF can project either a 650 or 350 lumen beam of white light with a peak intensity of either 95,000 or 55,000 candela, respective to your choice of battery. Despite being one of the smaller SureFire rifle light options, it’s impressively powerful, offering either 45 minutes or 1 hour of constant run time. And, when powered by an 18350, they can throw light out up to 616 meters away, and up to 469 meters away when powered with a CR123A.
M340C
The M340C Mini Scout Light is the standard variant of the M340. Compact, durable, and above all, bright—the M340C is only compatible with CR123A batteries, and it projects a 500-lumen beam of white light with a peak intensity of 7,600 candela. As such, it doesn’t project light as far as the other scout lights mentioned so far, as it only throws light out to 175 meters. While that’s not a short distance by any means, it’s worth pointing out to highlight that longevity isn’t what this light was designed for. Because of its lower candela count, the M340C projects a wider, less concentrated beam of light, meaning it offers more flood than throw, making it better suited for illuminating wide expanses rather than pinpointing the light on a specific target.
M340V
IR illumination is the undisputed king of illumination when shooting at nighttime, allowing you to effectively illuminate your target without giving your position away, and the M340V Mini Infrared Scout Light does it without bogging down your rifle setup. Like the standard M340C, it’s powered by a single CR123A battery and has an exceptionally durable construction. And like its big brother, the M640V, it can freely switch from projecting white light to IR light. While it does have a marginally weaker 250 Lumen white light projection with a peak beam intensity of 9,300 candela, it’s still more-than-bright enough for most applications.
That said, its IR capabilities are what make this light so sought-after. In its IR mode, it projects a 100 mW (860 nm) beam of IR light that’s only visible under NODs. When used as a dedicated IR illuminator, it offers up to 6 hours of continuous illumination, making it a solid pick for compact hunting and nighttime duty rifles.
Choosing the Right Light for Your Setup
We’ve gone over a bunch of different lights, each of which with their own unique capabilities and features. But which one is the best rifle light for your setup? In all honesty, it depends entirely on what you want out of your rifle, as different Scout Light models cater to different applications. That said, we can at least point you in the right direction.
If you have a longer rifle build, you can get away with using the larger M640 series of weapon lights. Not only are these lights more powerful, but they’ll provide you with the brightness, throw, and battery life that’s best fit for such rifles. If you want a light that has a lot of throw, the M640DF Turbo is the move—its higher candela count and narrower beam is highly effective at spot-illuminating specific targets. In contrast, the standard M640DF and M640U offer more flood, making them better at flooding an area with light, making them better for defensive and duty applications where you’re more likely to be maneuvering around rooms and other enclosed spaces. Lastly, if you’re planning to do any nighttime shooting under NODs, the M640V is your best bet.
The same general rule of thumb applies to the smaller M340 series of scout lights too. Models like the M340DF offer a great degree of versatility and have more throw than models like the M340C, which have more flood thanks to their lesser candela count. And, if you’re building a compact rifle for night vision, the M340V is a solid choice.
While neither light model is inherently better than the other, it’s critical to recognize the advantages each one offers. And, once you’ve narrowed down which light is best for your needs and setup, all you need to do is mount it to your rifle—something that’s rather easy to do considering every SureFire Scout Light uses the same mounts.
Conclusion
SureFire will forever be one of the top manufacturers of weapon lights, as all their weapon lights are manufactured with impeccable quality and precision. Their M640 and M340 Scout Light exemplify this, and with the multitude of options available to choose from, they’ve ensured that there’s something for everyone.
That said, it’s worth noting that they offer lights beyond their Scout Light series. Our SureFire Weapon Lights Guide goes in-depth on the various lights offered by SureFire. If you’re on the fence about whether a Scout Light is the right move for your next build, we recommend giving it a read.
