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KeyMod vs. M-LOK: The Next Generation of Accessory Mounts preview image
Jul 31 2023
7 min read

KeyMod vs. M-LOK: The Next Generation of Accessory Mounts


When it comes to mounting accessories to your rifle, the traditional options have been the Picatinny rail or the Weaver mount. The Picatinny rail, while the most popular solution, has its drawbacks, particularly in terms of weight.

However, in recent years, two alternative mounting solutions have emerged: KeyMod and M-LOK. These systems were developed to address the weight issue and offer increased versatility. Introduced in the 2010s, both KeyMod and M-LOK are gaining popularity in the market.

So, what exactly are KeyMod and M-LOK, and how do they compare to each other? Moreover, how do they compare to other mounting systems? Keep reading to discover everything you’ve ever wanted to know about KeyMod and M-LOK.



KeyMod was designed from the start to supersede the MIL-STD-1913 accessory rail, also known as the Picatinny Rail. It was first developed by VLTOR Weapon Systems and released through Noveske Rifleworks in 2012. It has since become open source, meaning it’s free to use by the firearms accessory industry.

The name comes from the two main characteristics of the mount. “Key” comes from the shape of the slots, which look like a keyhole. And “Mod” refers to the fact that the rail is meant to be modular.


Mlok rail

M-LOK is short for Modular Lock. This system was developed by well-known firearm accessory company Magpul Industries in 2014 as a replacement for the previous Picatinny rail system and an alternative to KeyMod.

Magpul’s polymer accessories were not very compatible with KeyMod’s nut, so Magpul developed its own system. M-LOK uses a series of T-shaped slots positioned at intervals along the length of a mounting rail.

Unlike KeyMod, M-LOK is not open source, but Magpul does allow licensing free of charge.

Key Differences Between KeyMod and M-LOK

keymod vs mlok
Left: M-LOK; Right: KeyMod – Image provided by Lucky Gunner

Both KeyMod and M-LOK are popular modular locking accessory mounting systems, but they do have a few key differences.


The KeyMod system was introduced in 2012 by VLTOR Weapon Systems and features key-shaped slots that run perpendicular to the mounting rail. These slots have a uniform size and spacing, allowing for easy attachment of KeyMod-compatible accessories.

The system was designed to simplify the attachment and detachment of accessories and reduce weight by eliminating excess material. KeyMod accessories attach to the rail by inserting a special KeyMod nut into the slot and then threading a screw through the accessory and into the nut.

The M-LOK system was introduced in 2014 by Magpul Industries as a replacement for the KeyMod system. It features T-shaped slots that run parallel to the mounting rail. The T-shaped slots are longer than the key-shaped slots on the KeyMod system and have varying spacing between them depending on the manufacturer.

This allows for greater flexibility in accessory placement and attachment. M-LOK accessories attach to the rail by inserting a special M-LOK nut into the slot and then threading a screw through the accessory and into the nut.

Ease of Use

Both KeyMod and M-LOK are designed to simplify the attachment and detachment of accessories.

However, M-LOK is generally considered to be easier to use than KeyMod because of its simpler design. The T-shaped slots on the M-LOK system allow for accessories to be quickly and easily attached or detached by simply sliding them into place and tightening the screws.

With KeyMod, the user must align the key-shaped slots on the accessory with the attachment points on the rail, then insert a KeyMod nut into the slot before tightening the screws. Alignment can be more difficult, especially for shooters with difficulty keeping their hands steady.


Both KeyMod and M-LOK are designed to be durable and withstand the rigors of firearm use. However, some experts believe that the M-LOK system may be slightly more durable because of the way that accessories are attached.

With M-LOK, the screws used to attach accessories are inserted through the T-shaped slots and threaded into metal nuts located underneath the rail. This design may provide a more secure attachment point than the KeyMod system.

However, some argue that the KeyMod system is just as durable as the M-LOK system and has been tested extensively in real-world scenarios.


In the past, one advantage of the KeyMod system was that due to being around longer than the M-LOK system, there were more accessories available that were compatible with the KeyMod system.

However, the popularity of the M-LOK system has increased dramatically, and many manufacturers are now producing accessories that are compatible with both systems. In fact, the M-LOK system is more popular these days, so there may be even more M-LOK accessories available.

Some manufacturers have even created adapters that allow users to switch between KeyMod and M-LOK accessories on the same rail.

KeyMod Pros & Cons

  • Designed to eliminate excess material to reduce weight
  • Accessories are quick and easy to attach and detach
  • Allows accessories to sit flush against the rail for a lower profile
  • Not as popular as it once was, so available accessories may be declining
  • Accessories can only be attached to the rail where slots are located
  • Polymer may be less durable than other materials

M-LOK Pros & Cons

  • T-shaped slots  allow for more flexible placement of accessories
  • Increasing popularity, so there should be plenty of compatible accessories
  • Allows accessories to sit flush against the rail for a lower profile
  • M-LOK-compatible accessories can sometimes be more expensive
  • Mounting accessories can be more complex
  • Can be significantly heavier than KeyMod, depending on the number of slots

Other Alternatives to Consider


Browning X-Bolt Picatinny Rail 300 RUM & 300 PRC Picatinny Rail

The Picatinny rail system (also called the MIL-STD-1913 rail) is a standardized system for attaching accessories to firearms. It uses a series of slots with a consistent width and spacing, allowing for a wide variety of accessories to be mounted in various locations on the rail.

However, you don’t necessarily have to choose between Picatinny and KeyMod or M-LOK, as many handguards will have a Picatinny rail along the top, then KeyMod or M-Lok slots along the sides.

Furthermore, there are plenty of Picatinny rails available that can be mounted to either KeyMod or M-LOK rails, so you don’t have to totally give up on your Picatinny accessories altogether.


Weaver AR Flat Top Riser Rail 20MOA 99675

Similar to the Picatinny system, the Weaver rail system uses a series of slots with a consistent width and spacing, but with a narrower profile than the Picatinny rail. This system is less commonly used than the Picatinny or KeyMod/M-LOK systems.

Direct Mount


Some firearms and accessories are designed to be mounted directly to the firearm without the use of a rail system. For example, a scope may be mounted directly to a receiver using screws or other fasteners.


Does the military use KeyMod or M-LOK?

The US military has used the M-LOK system since 2017. Many other militaries and law enforcement organizations use M-LOK, and this system has surpassed KeyMod in popularity among military and LEO organizations.

Is M-LOK better than Picatinny?

It’s not necessarily accurate to say that M-LOK is better than Picatinny or vice-versa, since it depends on the use and preference. Picatinny may be better when durability and compatibility with a wide range of accessories are critical. M-LOK may be better when weight, profile, and flexibility in accessory placement are important.

Is KeyMod compatible with Picatinny?

KeyMod accessories can be attached to Picatinny rails using adapters, which are readily available and easy to install. However, adapters add weight and bulk and may reduce the overall stability and security of the accessory.


One cannot say that either KeyMod or M-LOK is necessarily better than the other. The choice between the two ultimately depends on the intended use and personal preference.

KeyMod offers a lightweight, easy-to-use system that is highly customizable, making it an excellent choice for those who value flexibility and ease of use.

M-LOK, on the other hand, is versatile and attaches more securely, making it ideal for those who prioritize stability and security.

Ultimately, by carefully considering your needs and weighing the pros and cons of each system, you can make the decision that will help you get the most out of your firearm and accessories.

Written by Megan Kriss
Megan Kriss photo Megan has been an avid recreational shooter since she was a young child and she's thrilled to have the opportunity to combine this love with her passion for writing. Megan Kriss is a seasoned writer and firearms enthusiast with contributions to a variety of publications, including Pew Pew Tactical, American Firearms, A Well-Armed Woman, Recoil, and Faxon Firearms. In addition to firearms, Megan also enjoys writing about pets, outdoor recreation, and other lifestyle topics. When she's not busy writing, Megan enjoys tabletop games, reading, and being outdoors. She shares her Georgia home with her partner, dog, and two cats.


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