A little over a year ago, we posted a breakdown of the differences between Picatinny and M-LOK rail systems, and what the relative advantages of each were.
This time around, we’re going to take a closer look at KeyMod vs. M-LOK rail systems, with a breakdown of the differences between the two, and how they stack up against each other.
So let’s get into it.
What’s the Difference Between a KeyMod and M-LOK Rail System?
If you’re not familiar with either KeyMod or M-LOK rail systems, it’s actually fairly easy to get the two confused. They are, in many ways, much more alike than different, and much more like each other than either is similar to a Picatinny rail system.
In the Picatinny rail system, there are a series of rail ridges and slots. This the Picatinny system has more or less in common with Weaver rails. In both the KeyMod and M-LOK configurations, there are a series of slots machined into a flat surface.
At a glance, the way to tell the difference between a KeyMod and M-LOK system is through the shape of the slots. M-LOK slots are long and symmetrical, whereas KeyMod slots are shaped something like a pear, with a rounded end.
The KeyMod system was developed in collaboration between VLTOR Weapon Systems and Noveske Rifleworks. It was released in 2012, making it a relative newcomer (compared to the Picatinny system) which aims to standardize mounting systems.
KeyMod is an open-source design, so that anyone can copy the design of the mounting system or make attachments for it without needing to pay for a license.
The KeyMod system diverges from the Pic rail system in that, rather than having a handguard with a separate rail system attached, the KeyMod system is the handguard itself and has rail slots machined into it. This allows attachments, and Pic rail adapters, to be mounted anywhere on it, as needed.
As for M-LOK rail systems, these were designed and developed by Magpul Industries and released in 2014, just a bit after the KeyMod system was released. M-LOK, which stands for Modular Lock, was designed as a competitor to KeyMod, with the intention of working better with non-metallic mounting surfaces and polymer accessories.
While KeyMod is open-source, M-LOK is not. It is, however, free-licensed by Magpul Industries, which means that M-LOK rails and standard mounting accessories are still fairly widespread.
Both KeyMod and M-LOK rail systems accept similar mounts but the process is slightly different for each.
For KeyMod systems, you must first make sure to orient the attachment properly. There is one end that must face the muzzle. Seat the accessory in the slot, slide it forward into the narrower part of the slot, then screw it in to secure it.
For M-LOK accessories, insert the T-nut into the slot, use a hex wrench to rotate the nut into the slot 90° till it is in the locked position, then tighten it to the appropriate torque setting.
With this said, there are several advantages and disadvantages to each type of rail system.
Advantages of M-LOK Rail Systems
M-LOK rail systems offer users a number of advantages not only over traditional Picatinny rail systems but also over KeyMod rails.
For one, the M-LOK offers great aesthetics which some appreciate. M-LOK rail systems are also compatible with many accessories that won’t work with a KeyMod, namely polymer accessories.
The M-LOK system also uses bi-directional swivels on its locking lugs, offering a really secure interface - although it is hard to draw a distinction between the two in terms of which one is better.
It is also worth noting that a USSOCOM performance assessment, which compared both KeyMod and M-LOK rail systems with respect to endurance, rough handling, dropping, failure load, and repeatability, determined that the M-LOK system outperformed the KeyMod through 3 of 5 parameters.
Drawbacks
While this isn’t much of a disadvantage, it’s pretty hard to remove accessories from an M-LOK rail system because it’s hard to access the locking lugs on the inside of the rail panel. Really, that speaks more as an advantage to the security of the system, though.
Advantages of KeyMod Rail Systems
One of the greatest advantages of KeyMod rail systems is that they are incredibly lightweight. In competition, or for days in the field, every single ounce counts.
KeyMod rail systems are also smooth and slim, trimming down the platform’s overall profile. Since they are smooth, they are also more comfortable to grip with bare hands than a Pic rail would be. That said, this advantage is shared with the M-LOK system.
Also, the interface of the KeyMod system, with its slots that have one wide and one narrow end, is inherently secure. Once the bracket is secure and appropriately tightened, the interface is very strong and reliable.
Another advantage is the low cost and wide availability of KeyMod systems and accessories, which is a result of the open-source design.
Drawbacks
With all of that said, there are some potential drawbacks to KeyMod rail systems. For one, the small size of some minor parts used in KeyMod mounts are easy to lose, especially if they work free.
Some users have reported that KeyMod rail systems have failed some drop tests. That is, some platforms with KeyMod accessories attached, shed them when dropped.
KeyMod rail systems themselves can also fracture when dropped, which is even more of a concern.
KeyMod systems (though relatively widely supported by this time) do not have the same level of support as other systems, like Picatinny and M-LOK rail systems.
Get Them Both Here (Plus Picatinny-Rail Equipped Assembled Uppers)
As you can see, there are a whole lot of positives to the use of both KeyMod and M-LOK rail systems, and not a lot of disadvantages to either, especially when comparing them to Picatinny rails.
We carry Picatinny, KeyMod, and M-LOK rail handguards, as well as shooting accessories for these systems. Take a look through our full collection, as well as our collection of assembled uppers which are complete with handguards, and get in touch with us at Sales@MCSGearup.com if you need any assistance.