If you want to attach accessories to your AR-15, you’ll be faced with the same dilemma I was: do you go with the KeyMod or M-LOK attaching system?
For years, the Picatinny rail stood as the primary method for attaching various accessories such as lights, lasers, and foregrips to firearms (both rifles and handguns).
As successful as it was, the Picatinny system still had its drawbacks.
The addition of a Picatinny rail onto an AR-15s handguard or forend often resulted in added weight, which some people (including myself) found rather bulky and uncomfortable.
This led to a new generation of accessory mounting systems in the 2010s for AR-15s and other semi-automatic rifles.
These new mounting systems were designed to be lighter than the Picatinny system while also offering increased flexibility when it came to mounting accessories.
The two primary mounting systems that have attracted more attention than any other are
The KeyMod and M-LOK systems.
Both of these systems are based on a slot design rather than the rail system employed by Picatinny (and Weaver) mounts.
But is one better than the other?
In this article, I’ll attempt to answer that question.
Together, we’ll explore both the KeyMod and M-LOK systems in clear detail, and then at the end we’ll see if there’s a winner.
KeyMod Overview
The KeyMod mounting system was developed between Noveske Rifleworks and VLTOR Weapon Systems in 2012.
This system was the result of these two companies attempting to create a new universal attachment system that could either replace or at least supplement the Picatinny system.
The KeyMod system actually permits the attachment of Picatinny rails to the handguard as needed, but it also features its own style mounting slots with a keyhole profile.
This profile consists of two components: the KeyMod slot and the KeyMod nut.
KeyMod’s innovation lies in its ‘open source’ approach, facilitating the creation of rails by various firearm manufacturers using the same design without requiring additional rights fees.
The release of the KeyMod Tech Data Package as an open-source resource to the public, for instance, allowed for standardized modularity akin to the Picatinny rail.
This collaborative effort within the firearm industry and community has led to a significant expansion in the firearm rail industry and has benefited modern gun owners across the board.
If anything, the M-LOK system like we’ll explore here soon was a result of this expansion.
Pros of the KeyMod System
- Lightweight Design
- KeyMod rails are exceptionally light, making them ideal for situations where weight reduction is crucial for improved aim and stamina.
- Enhanced Grip
- The slim profile of KeyMod rails allows for a secure grip on the handguard with the support hand. This enhances control and stability during firearm handling.
- Compatibility
- KeyMod rails are compatible with a wide range of accessories. They offer users the flexibility to mount optics, sights, and ergonomic grips without sacrificing customization options.
- Secure Attachment
- KeyMod accessories are easily attached and secured using lug screws, They provide a fast, safe, and secure locking method for accessories.
Cons of the KeyMod System
Risk of Losing Parts
Small locking parts used to secure KeyMod accessories can be easy to misplace and challenging to replace. This can lead to inconvenience for users.
Separation During Drop Testing
In drop tests, KeyMod accessories and rails have been known to separate from the handguard due to the extreme lightweight nature of the design. This can result in potential functional issues and difficulty in reattaching accessories.
Vulnerability
The smaller size of KeyMod slots makes them susceptible to fractures or breaks if the handguard is dropped. This poses durability concerns and potential difficulties in reattaching locking nuts.
M-LOK Overview
Magpul, a very prominent name in the world for firearm accessories and components, recognized the potential of the KeyMod system developed by VLTOR and Noveske.
Two years after the KeyMod system was unveiled, Magpul introduced its own proprietary system, known as the M-LOK (short for Modular Lock) in 2014.
The M-LOK system offers a similar direct accessory attachment feature as KeyMod but with improvements that are designed to better accommodate non-metal mount surfaces.
Unlike KeyMod, which is open-sourced, M-LOK is patented by Magpul Industries and operates under a free license model.
This means that gun manufacturers must obtain a license from Magpul to produce M-LOK-compatible handguards and accessories on their weapons.
Pros of the M-LOK System
Aesthetic Appeal
The M-LOK system offers a sleek and modern appearance. Some believe this enhances the overall look of firearms.
Functionality
M-LOK provides a secure and reliable mounting solution for accessories. This helps ensure they stay firmly attached.
Compatibility
Developed by Magpul, M-LOK addresses compatibility issues with certain polymer accessories and ensures seamless integration.
Easy Attachment
The unique slot design of M-LOK allows for easy attachment of accessories, which enhances user convenience.
Enhanced Locking Mechanism
Bi-directional swivels in the locking lugs of M-LOK improve the locking mechanism. This provides added security.
Cons of the M-LOK System
Difficulty in Adjustment
As more accessories are mounted, accessing the locking lugs within the rail becomes more challenging with the M-LOK system. In other words, making adjustments to your accessories can become more difficult.
Limited Adjustability
Users may encounter challenges when attempting to adjust the placement of rail panels, handstops, or foregrips due to the design of M-LOK.
Is One Better Than The Other?
Now it’s time for the big question: is KeyMod or M-LOK the better attachment system?
Perhaps the United States military can answer this question for us.
In 2016, the United States Special Operations Command (US SOCOM) conducted rigorous testing to compare the performance of the KeyMod and M-LOK accessory mounting systems.
The evaluation aimed to assess factors such as repeatability, endurance, rough handling, drop resistance, and failure load to determine their effectiveness in military applications.
While both systems passed the Endurance and Rough Handling tests, the M-LOK system demonstrated superior repeatability, exhibiting minimal MOA shift when accessories were removed and reattached.
In drop tests, the M-LOK accessories also remained securely attached 100% of the time, whereas KeyMod accessories maintained attachment only 33% of the time.
As a result, the M-LOK was selected for integration into the Suppressed Upper Receiver Group and Advanced Sniper Rifle programs.
Despite KeyMod’s performance shortcomings in the testing, it remains available for applications outside of military use, although M-LOK is more widely adopted by civilians, law enforcement, and the military alike.
Is There A Winner?
When it comes to your own use, only you can decide which system you want to use for your rifle.
At the end of the day, I believe both designs work, and the KeyMod system deserves credit for helping to revolutionize the mounting systems for rifle accessories as a whole.
But the M-LOK system essentially built on what KeyMod started and has proven to be a bit more durable. That’s perhaps the biggest reason why it’s been more widely adopted.
Which system do you think you’ll go with? Let us know below!
