When it comes to handguards, you’ve got a few options. For many, the military standard 1913 Picatinny rail system is their first, only, and last choice and they don’t see the need to upgrade further. For others looking for the latest and greatest, the Keymod rail system might be an option. But in recent years, a variety of private manufacturers have created a myriad of handguard options. One in particular has garnered more than its fair share of attention: the M-LOK.
The M-LOK rail system has exploded onto the scene, offering a dynamic new way of mounting rail covers and AR accessories. They say that necessity is the mother of invention, so what was the necessity that inspired this handguard design?
As a leading provider of AR-15 rail grips, we’re always exploring the development of related products, including the M-LOK platform. Let’s take a look at the origins of this popular handguard.
In 2007, Magpul helped to design the Masada Concept Rifle. Eventually, this rifle would go on to become the Bushmaster ACR, and while it failed to impress the military in trials to replace the M4 Carbine, it did offer some innovative new features that intrigued Magpul and other manufacturers.
In particular, the rifle featured three slots on the handguard that allowed for accessories to be quickly mounted to the forend. Based on this design, Magpul released their MOE handguard line that utilized that same slot system. After several years of R&D and trial and error, Magpul eventually refined the MOE rail system. The result was the release of the M-LOK rail system in 2014.
The Modular Lock System — or the M-LOK system, for short — was designed in response to the Picatinny rail system. Picatinny rails make use of a series of slots and ridges along the sides of the handguard. Accessories like foregrips, handstops, optics, and lasers can be mounted to these rails. The useful nature of this system means that it has been deployed with militaries and police forces around the world for decades.
The system is undoubtedly effective but isn’t without its failings. For instance, this rail system is fairly heavy and bulky. Newly-made handguards have pronounced points which can hurt the operator. The designers of M-LOK decided to create a system that addressed these issues, doubling down on the benefits at the same time.
The final vision was to create a rail system that allowed more opportunities to attach accessories while still being lightweight. In order to realize this goal, Magpul created a handguard that used rectangular cutouts rather than raised ridges and rails. AR accessories are fitted to the rifle by using the T-shaped lugs on the bottom of each accessory. The lugs are pushed through the cutouts and secured in place by tightening them with an Allen key. The long, rectangular shape of the cutout allows for the accessory to be moved forward and backward to meet the operator’s needs.
The immediate benefit of this layout is that any AR accessories can be quickly mounted to or removed from the handguard. This is perfect for AR-15 owners who may use one rifle for a variety of different purposes and have different accessories for different styles of shooting.
The success of the MOE, and later M-LOK rail systems, wasn’t limited to just the private sector, however. In 2017, the Naval Surface Warfare Center announced that it was beginning trials to replace the iconic Picatinny system. These tests would pit a variety of modular rail systems against each other, testing things like durability, retention, and ability to maintain an optic’s zero after being removed and reattached.
The results of the test found that the M-LOK rail system was a clear favorite, as it far and away excelled in all areas of the test. When compared to other modular rail systems, the M-LOK system was the easiest to use and maintained an optics accuracy closest to zero. Accessories could be mounted, removed, and mounted again to the same location on the M-LOK rails and the point of aim would only shift 1.3 MOA. Moving accessories on the M-LOK handguards did not diminish the effectiveness of AR accessories like scopes, lasers, and other optics.
In fact, in drop tests, it was found that the M-LOK handguards also retained their accessories better than other modular handguards. It was only when subjected to high pressure or severe abuse that the M-LOK rail would release its attachments.
One of the advantages of the M-LOK system is the unrivaled third-party support for it. Dozens of accessories have been developed for these handguards to make them easy to manipulate and have a greater sense of recoil control over.
Naturally, RailScales has developed a line of rail covers, grips, and hand stops that are specifically designed for your AR-15 handguards. Browse our complete selection of products here and order them today!
Once you've decided on a rail system, you'll want to customize it so that your new gun meets all of your requirements. This means you may need to choose the right type of rail system for your firearm. Fortunately, at RailScales®, we're here to assist. We provide a number of distinct customization choices, including our signature RailScales. We realize that customizing your AR-15 is quite personal, which is why we try to accommodate our customers in every way possible. As an example, if you eventually choose to acquire a rifle with an M-LOK rail system, you won't go wrong with our G10 RailScales® in M-LOK. These one-of-a-kind scales are what started it all, and they may give you added grip, heat protection, and help you personalize your rifle. They're easy to install (you'll receive instructions), and they never require you to remove the rail system from your gun!
The KeyMod rail system has several advantages over the M-LOK system, but it also has a few drawbacks. One of the most significant disadvantages of the KeyMod rail system is that it lacks nearly as much industry backing as the M-LOK system does. That isn't surprising, especially when you consider that the M-LOK system is backed by one of the biggest firearms accessory manufacturers in the world – Magpul. But perhaps a lack of industry backing isn't so bad after all, as it has forced manufacturers to come up with creative solutions. For example, there have been a number of companies that have introduced KeyMod compatible parts and accessories that utilize slings. The KeyMod rail system has several drawbacks. The lack of many accessories designed for this sort of rail system is one of them. This may be due to the fact that when SOCOM subjected the KeyMod system to testing, it was discovered that the rail was simpler to break. However, it's worth noting that SOCOM went all out with the testing, using a very extreme test that is not reflective of general use. The KeyMod system has also been criticized for its weak fasteners. Unlike the screws used in the M-LOK system, the KeyMod screws are hex head bolts that can become loose over time.
The M-LOK system, like KeyMod, allows accessories to be mounted at the front or rear of any given slot. However, there are many individuals who find it difficult to attach gadgets to the M-LOK platform, at least when compared with the KeyMod system. Some people may find it simpler, but at the very least, before attaching accessories, removing the rail completely is easier. It's been observed that the M-LOK rail system is a little heftier than the KeyMod system. Keep in mind that the KeyMod system was created to reduce weight; if you're trying to build the lightest AR-15 possible, KeyMod may be a better option for you. A number of manufacturers decided to make accessories specifically for M-LOK, making this system slightly more popular than KeyMod. However, since then, not much has been done in this space, and KeyMod has taken the lead. Interestingly, Magpul licensed the M-LOK system to other companies, which could explain why it hasn't caught on as much as KeyMod.
No matter what you need, you can always count on the team at RailScales to provide you with the best quality accessories in the business. You can explore our collection of G10 RailScales, custom grips, and more! If you have any questions about M-LOK or our other offerings, you can reach out to our team at any time.
Magpul MOE M-LOK handguard on a user-assembled AR-15 semi-automatic rifle
M-LOK, for Modular Lock, is a firearm rail interface system developed and patented by Magpul Industries. The license is free-of-charge, but subject to an approval process.
M-LOK allows for direct accessory attachment onto the "negative space" (hollow slot) mounting points, and is a competing standard to VLTOR's open sourced KeyMod system for replacing the ubiquitous Picatinny rail in some applications.[1] Compared to the Picatinny rail system, both M-LOK and KeyMod enable the user to have a slimmer, lighter, smoother and more fenestrated handguard/fore-end with accessories mounted only where needed, whereas a Picatinny handguard typically will have rail slots for its whole length, resulting in a heavier and bulkier handguard with sharp edges and poorer barrel ventilation.
The M-LOK system can be seen as an evolution of the Magpul Original Equipment (MOE) system, but the two are not fully compatible. Though newer M-LOK accessories can be used on older MOE slot handguards if an adaptor plate is used, there is no adaptor available for using older MOE accessories on the newer M-LOK handguards.
History
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A prototype of the MOE slot was revealed by Magpul in late 2007 together with their Masada Concept Rifle (which would later be known as the Adaptive Combat Rifle). The MOE slot system was released by Magpul in 2008 as a feature on their MOE handguards, and at the same time compatible accessories such as Picatinny rail sections, direct MOE mounted light mounts, grips, bipod studs, etc. were released.
The MOE slot standard was never officially released, and a drawback to the system was that the rear side of the panel had to be accessed in order to mount accessories, limiting its application. The MOE slot system uses a weld nut which has to be placed manually on the inside of the handguard before mounting, making the slot system unsuited for applications such as free-floating handguards[citation needed]. Also, depending on the accessory item, the spacing increments between the MOE slots were not small or uniform enough to adjust the desired placement of accessories.
Colt Canada MRR with M-LOK rail handguardAcknowledging shortcomings of the MOE systems, Magpul drafted M-LOK as a new and improved mounting standard which was released in 2014 replacing the existing MOE slot. The M-LOK rail specification included metric dimensions instead of imperial, and utilizes a T-slot nut capable of only 90-degree rotation, reinforced by thread-locking fluid, making it suited for applications on free-floating handguards. It was designed to work with both metal and polymer parts.
In 2016, Colt Canada developed and released the Modular Rail Rifle (MRR) that uses a monolithic upper receiver with the M-LOK attachment system.[2] In 2017, several companies produce M-LOK handguards as well as accessories like Picatinny rail strips, vertical foregrips, bipods, sling adaptors, and flashlight mounts.[3][failed verification]
In 2017, a summary report of testing conducted by NSWC-Crane for USSOCOM indicated that, while comparable in endurance and rough handling testing, M-LOK greatly outperformed Keymod in repeatability, drop testing and failure load testing.[4]
In 2018, the Upper Receiver Group-Improved (URG-I) is a U.S. Army Special Operations Command (USASOC) program to further improve the durability and reliability of the SOPMOD Block II by introducing additional component improvements. First fielded in the same year, the main improvements are the lighter Geissele Mark 16 free-float rail that incorporates M-LOK as the mounting method and a Daniel Defense cold hammer-forged barrel that returns to the lighter "government" profile contour as well as a mid-length gas system. Used on the M4A1 carbines then MK18 URG-I variant CQBRs.
Licensing
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M110A1 SDMR featuring a Geissele M-LOK rail handguard A STNGR USA 15 in (381 mm) HWK M-LOK handguard on a civilian semi-automatic AR-15 style rifleWhile M-LOK is licensed free-of-charge, it is not open source, and thus manufacturers must acquire a license from Magpul before making products using the M-LOK standard. Magpul claims this gives them more control in assuring that all M-LOK products are made to specifications ensuring compatibility. Program participation is open to any interested manufacturer.[5]
Note that although Magpul describes the license as a "free license", the meaning does not match the more common meaning originally established in computer circles. The computer "free license" refers to a freedom to use,[6] while Magpul only conditionally offers the license for free (analogous to a source-available freeware).
NATO standards conform military issued assault rifles like the CAR 816 have semi-automatic only export versions featuring M-LOK rails on the handguard to better meet civilian market preferences in the United States.[7][8][9]
Technical specifications
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Rail specifications
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The slot dimensions (used on handguards, etc.) are available on the web.[10] The slots provide metric 20 mm (0.79 in) length intervals, and accessories can be mounted either within a slot or bridging between slots, making it possible to adjust the position of accessories in smaller intervals than the length of the slot. The slots on an M-Lok handguard are approximately 32 mm (1.260 in) long and 7 mm (0.276 in) wide and space 8 mm (0.315 in) from each other. The radius of the corners is approximately 2.38 mm (0.094 in).[10][11][12]
Attachment specifications
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The quarter-turn T-slot nuts have different torque specifications depending on the handguard material:
Attachment screws made by many U.S. manufacturers are often either #8-32 TPI or 10-24 TPI UNC threads, which respectively have major thread diameters of 0.1640 inches and 0.1900 inches (4.166-0.794 mm and 4.826-1.058 mm expressed in metric designation). Many M-LOK screws on the international market instead use either M4 or M5 metric threads to reduce cost.
The tool required for mounting, in addition to the thread size, also depends the screw head type. Hex keys are used extensively in the firearms industry, but metric and imperial hex keys as a general rule are not compatible. It is possible to damage the tool and screw by selecting a tool that is too small for the fastener, which can be done by using an imperial tool on a metric fastener, or the converse. An exception to this is 4 mm hex keys, which are almost the exact same size as 5⁄32 in (3.97 mm). In many industries, this makes 4.0 mm (5⁄32 in) hex keys preferred for consumer products because end users can successfully use an imperial key on a metric fastener, and vice versa.
Hex key spanner (wrench) size • Button head cap
screw
9
⁄64
" (3.57 mm)3
⁄32
" (2.38 mm) #10-245
⁄32
" (3.97 mm)1
⁄8
" (3.18 mm)While screw and slot dimensions are available on the web, the T-slot nut dimensions are currently under review by the US State Department to determine whether it should be regulated by ITAR, and until it is clarified drawings are only available to US citizens.
M-LOK handguard and attachment parts
M-LOK approximate slot dimensions. (Primary measurements in millimeters, inches in parentheses.)
See also
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References
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