FOURSEVENS Maelstrom X7 Review


Flashlight Enthusiast
May 5, 2010
Hove, UK
The FOURSEVENS Maelstrom X7 that I have for review has the original 4sevens branding

FOURSEVENS are in the process of updating the design of their website and product naming/branding which can be seen at the new FOURSEVENS website (rather than 4sevens).

The new logo.

Initial Impressions:

The market is flooded with single 18650 lights in a ‘tactical’ form with 1” weapon mountable tube, so is this just another one or does it stand out from the crowd?

From first handling the X7, one design feature that makes it feel different is the head design. The X7 uses a twist interface to change modes and needs a grip ring at the front. This grip ring is a thick section with the same knurling as the body of the light, and is the same diameter as the bezel. This design feature gives the Maelstrom X7 a feeling of solidity usually not present in this type of light. Although not adding significant weight, the solid feel gives you the impression that you could happily hammer in nails with it.

What is in the box:

One of FOURSEVENS trademarks is the velvety finish of the box. Once you have had your first FOURSEVENS light you will know how this adds a unique feeling of quality, and the contents do not disappoint.


The light is contained in a two part plastic carrier, shown here with two halves side by side. The light and battery pack in one half and the holster, lanyard, instructions, alternative black bezel and spares in the other. The battery pack supplied consists of two FOURSEVENS CR123s held together with a shrink wrap.


The X7 is supplied in its default configuration with stainless bezel, clip and tactical ring, all of which can be changed / removed.



Looking straight into the lens showing the XML emitter.


Also included with the X7 for the review is the Maelstrom remote tail-switch (this is a separate optional accessory)


A detail of the inscription on the remote switch.


Looking inside:

With the tail-cap removed the positive and negative contacts are visible. The contacts are very similar with a gold plated slightly domed contact surrounded by a hard rubber shock absorber. This design should make the X7 very resilient even if used mounted on high power weapons.


Shown here with the battery tube threads and double o-rings visible.


Removing the battery tube reveals the four stage switch which consists of four contacts at different heights which progressively make contact with the head of the battery tube as you tighten it.


Modes and User Interface:

One of the Maelstrom X7’s features is its four-stage switching activate by simply gradually tightening the head to increase brightness or loosening to reduce brightness.

In total there are 8 modes available in sets of 4.

By default, the steady modes are available, starting with the head fully tightened, High (480lm), then for each approximate 75 degree loosening of the head, the mode switches to Medium (270lm), Low (30lm) and Moonlight (0.3lm). Further loosening of the head will not change mode and will ultimately unscrew the head completely.

To access the special flashing modes, you need to change between High and Medium quickly four times. After this there are three flashing modes and high - Beacon, S.O.S., Strobe, High. To return to the steady modes repeat the rapid switching of the two tightest position modes.

As the mode switching is all done with twists, the tail-cap switch only turns the light on and off. The X7 has a forward clicky for momentary operation.

Batteries and output:

You have several options with the X7, 1 x 18650, 2 x CR123 and 2x RCR123 are all supported (Operating Range: 2.7V-8.4V). For regular use the 18650 will give you the best runtimes and economy, for high power weapon mounting, generally primaries are the better choice.

FOURSEVENS state that flat top 18650s will not work, and you must use button top. However, I have been using the new AW 3100mAh battery to access all output modes with no issues at all, and the 3100mAh AW has a flat top. Looking at how the X7 four stage switch works, flat top 18650s shouldn’t work, but this particular AW does, maybe because the flat top itself is quite small. Use a button top cell for reliable operation.


The CR123 pack supplied by FOURSEVENS is a very good idea. The two individual CR123 cells are held firmly together as a pack, making battery change simpler.

The X7 output levels are regulated but rather than step down when the battery can no longer provide the necessary power, the X7 gradually dims down to the next level. Using the AW 3100mAh, the High output level reduced to the same as the Medium when the AW 3100 mAh battery has reached 3.4V. Remember that this AW cell still has about 50% usable power when it reaches 3.5V as it is the new NNP technology.

After another couple of hours Med dimmed to Low and the AW 3100mAh battery measured 2.84V.

Using higher voltage combination of 2xCR123 or 2xRCR123 gives longer maximum output, but with only about half the runtime.

The new AWs provide very long runtimes and due to the power delivery of the NNP technology there is still a lot of capacity left when older cells would be about to run out. For the X7 this means you will not find yourself suddenly in the dark as the Medium and Low modes are maintained for a long time after High can no longer be used.

In The Lab

In an attempt to quantify the actual beam profile I developed the following test. There are probably many flaws in my method, but it is simple and easy to carry out and seems to provide a good enough comparison.

The method used was to put the light on the edge of a table 1m from a wall, with a tape measure on the wall. The zero of the scale is placed in the centre of the hotspot and a lux meter is then positioned at points along the scale, with the measurements recorded. Beam shots are often taken with the light shining on a flat white wall, so this method is simply measuring the actual intensity across the beam on a flat surface, not the spherical light emission.

The results are then plotted on a graph.

For the best throw you want to see a sharp peak with less of the distracting spill. For the best flood light the trace should be pretty flat.

Comparing the X7 to the Fenix TK21-U2 which has similar specification output, but is known for a slightly floody beam shows the X7 having significantly more throw.


Taking this a little further, I calculated an approximate factor to apply to the lux measurements, as each measurement gets further from the centre of the beam, it corresponds to a larger area onto which the light is falling. It seems to me that this should also be taken into consideration, so I applied these area corrections and came up with this odd looking graph.

The key quantity here is the area under the graph line. This should correspond to the total light output.


The beam profile graph initially makes it appear the X7 has far greater output, but using the area adjusted graph you can see the actual output is similar, but with a different distribution of light.

The beam

The previous graphs show how the X7 has much more throw than the Fenix TK21, however, it is still only a medium thrower compared to something like the Armytek Predator. This makes the X7 very versatile as it is neither flood nor extended throw, instead having a wide hotspot with reasonable throw.


The X7 clearly capturing the fact that I breathe!


Using the X7

The FOURSEVENS moonlight mode of 0.3lm is just right for night time forays and the reliable switching straight into the mode set by the position of the four stage switch means no accidental blinding by getting a higher output. Having a forward clicky, you can access any mode in absolute silence by half pressing the tail-switch. The Moonlight mode still exhibits the FOURSEVENS preflash, but this is not a problem in reality as the flash is so brief it doesn’t affect your vision.

Curiously, the X7 exhibits pre-flash in Low mode as well, where it first comes on in Moonlight (with pre-flash) and then steps up to the Low output.

Here I have captured the Low switch on sequence using a high speed camera running at 420 fps.

The X7’s holster is well thought out and has an excellent feature of a slightly ‘waisted’ design that takes the light bezel down. The waist holds the head of the light and retains the X7 even if you don’t close the popper of the flap.

The back of the holster showing the D-loop and Velcro-closing belt loop


A front view showing the waisted design.


In preparation for using gun mounted I have applied all optional changes. The clip is removed, the tactical grip ring swapped for a plain ring and the bezel changed to the plain black bezel to reduce reflections.


I’ve chosen to try the X7 out on a semi-automatic 12g shotgun with 7+1 capacity. Safety first, the breech-flag is visible, and the X7 has been mounted to the magazine tube using a simple mounting block.


Looking from the side. (This semi has a long 31” barrel is long for maximum velocity though is it slower to swing than a shorter barrel)


The remote switch has been mounted to the fore-end grip using two bands cut from bicycle inner tube which I find more resilient than other rubber bands. It is positioned to fall underneath my left thumb when the gun is up.


The rubber block proved less than ideal for mounting the X7 as it was not holding it firmly enough, two of them would work better, but I need to order another.

There is enough spill to allow for the shotgun to track a moving target, in this case rabbits, and the hotspot giving good definition of the bead against the background, making the X7 excellent for use with a shotgun at all ranges the gun is effective at. No sign of any hiccups due to the recoil when used with 32g cartridges unless your pressure on the remote switch drops.

On High, the X7 does build up a reasonable amount of heat, but due to the design of the head, it takes a while to become noticeable due to the good amount of metal present to soak up the heat. On Medium I didn’t notice any warming of the head as the heat-sinking easily dissipated the heat produced.

Changing modes does require quite a significant twist of around 75º per mode. To go from Moonlight to High does feel a bit of an effort and changing modes is a two handed job. There is no indication of where the mode change will happen, so with the light off the only mode you can reliably find is High, with the head fully tightened (though this is the mode most likely to be needed in a hurry). You can over-loosen the head and miss Moonlight mode, simply turning the light off, and Medium and Low would be guesses. However, what this interface does provide is a type of use where you have chosen an output level at leisure which is immediately available when needed without accidentally finding a different mode.

The extras included mean you can pick the configuration of bezel, ring, clip that fits your purposes best, although I keep swapping it around as I can’t decide!

I’ve found the X7 to be reliable, solidly built light with useful beam profile which does stand tall in the crowd of similar lights.

Review sample provided by FOURSEVENS.
AW cells provided by Andrew of AW.

I’ll update post 2 of this thread once I have some more comments to add....
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Flashlight Enthusiast
May 5, 2010
Hove, UK

On the golf driving range I've attempted to adjust the exposure to give a true likeness to what is seen by eyes partially adjusted to the dark. The light pollution from the neighbouring road means your eyes never adapt fully in this location, but the range markers give a good idea of the beam's reach.

Unfortunately there was a slight mistyness in the air so the true power and range appear reduced.


Zooming in to check the distance markers, the 100, 150, 200 and 250 yard markers can be seen


Hoping to get some more photos done soon.
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May 14, 2011
Really nice job! I have the G5 and it is a great light with incredible throw. I will say that the UI is clunky, somewhat imprecise and often a bother to use for a tactical light. That not withstanding i am glad I own it and 4sevens really backs their gear.


Flashlight Enthusiast
Feb 16, 2003
Houston, Texas
I have had mixed results using AW flat top cells. They work but not reliably.
I just purchased a few EagleTac 3100mah button top cells and they seem to work well. I would imagine that any of the actual button top cells would be very reliable in this light.


Flashlight Enthusiast
May 5, 2010
Hove, UK
Comments about flat top/ button top batteries updated.

For reliable operation a button top cell is required.


Newly Enlightened
Apr 30, 2012
I think I can honestly say those are the most accurate looking beamshot pictures I have ever seen. Nice job on the exposure.
What other lights do you have that you can do this with?


Flashlight Enthusiast
May 5, 2010
Hove, UK
I think I can honestly say those are the most accurate looking beamshot pictures I have ever seen. Nice job on the exposure.
What other lights do you have that you can do this with?

Thank you. I try to get the photos so that they represent the 'as seen by the naked eye' view as much as possible. In this review the local conditions were very misty and foggy for some time. This was the first opportunity to take photos that were not complete white-outs, and in fact the slight mistiness actually helps to show the beam itself.

My other reviews show other beamshots taken with the same principals in mind, but differing conditions mean the results vary slightly. I'm currently in the process of restarting the reviewing machine after taking a break for personal reasons so am hoping to post more reviews soon.