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KeyMod vs M-LOK

KeyMod vs M-LOK

February 01, 2019

It’s a fun time being able to play with the attachments and AR accessories for your rifle. What’s more, you have a virtually unlimited amount of customization with your AR-15. A decent bipod, flashlight, sight, and hand stop can help you get the most out of firing your rifle, but you have to be able to mount those components.

In this article, Rail Scales is going to share the pros and cons of the KeyMod and the M-LOK rails systems so that you can decide which is best for you. Each have their advantages, but like with everything in life, no system is ever “perfect.” However, you can find the best rail for you and your shooting needs.

KeyMod and M-LOK Compared

A Brief History

For Years, the standard accessory mounting system on AR-15 rifles has been the Picatinny rail. Still, the Picatinny rail is one of the most widely used rail systems in the industry, even though it poses some disadvantages that the KeyMod and M-LOK resolve. Nonetheless, the Picatinny rail system is still widely used because it has a straightforward, easy-to-utilize accessibility.

One of the disadvantages to the Picatinny rail is that it can add some unnecessary weight to your rifle, bulking it up in a way that’s not beneficial to your gun use. Placed on the front end of your rifle, it can make your AR-15 a little nose heavy.


Due to this single inconvenience, two resolutions were designed and distributed throughout the industry. The KeyMod and M-LOK rail systems. Both systems made the promise to cut back weight and add a wider range of mounting capabilities. Both systems also provided the ability to attach accessories to the handguard and not require to install a Picatinny rail across the gun. The ultimate advantage of both the KeyMod and the M-LOK is that you can add accessories to your gun exactly where you want them without any excess weight addition.

Which Rail System Is Better?

This is the one-million-dollar question, and it starts with you. Which system fits your needs the best? Across the gun industry, there is a fierce comparison between the two rail systems, but one must come out on top; it’s how the world works. With that being said, we’re going to share a brief history of each rail, as well as a brief history of each. Then, you will be able to make a decision on your own as to which rail system is the best for you.

The KeyMod Rail

As a universal interface system for firearm accessories, the KeyMod rail was designed to supersede the MIL-STD-1913 rail. They term KeyMod was coined by Eric Kincel when he worked for VLTOR Weapon Systems. The “key” related to the keyhole profile of the rail, and the “mod” referred to the modular accessibility of the rail. As an open sourced design, the entire firearm industry is at freedom to use and distribute it in the public domain.

KeyMod Pros

  • The rail system is smoother, and will not get snagged on seat belts, webbing, or other fabric that is brushed against the system. 
  • You add the rail system where you need to mount your accessories; nothing more, nothing less. 
  • The KeyMod rail system removes a ton of unnecessary weight compared to the Picatinny system.
  • The system is slimmer than a quad rail setup

KeyMod Cons

You will need tools to mount accessories and upgrades.
Cheaper accessory mounts may not conform to KeyMod specs.

The M-LOK Rail

The “M-LOK” acronym stands for Modular Lock. This rail system is a free licensed firearm rail interface system that is patented by Magpul Industries. It was developed by Magpul’s design team, which consisted of five individuals. The M-LOK design enables gun owners to attach accessories in the “negative space” mounting points.

In late 2007, magpul revealed a prototype of the MOE slot alongside their Concept Rifle (later known as Adaptive Combat Rifle). Later in 2009, Magpul released the MOE slot systems as a feature on their MOE handguards. Shortly after, the compatible accessory mounts for the Picatinny system were able to use the MOE system.


As the MOE system feedback rolled in, Magpul reconciled the system’s shortcomings and drafted the M-LOK system in 2014. The M-LOK system is made up of slots, not keyholes, and T-shaped nuts that lay across the slot and locking the accessory into place. Instead of making their design open source, Magpul decided to go with free licensing to any manufacturer that obtains permission ahead of time.

M-LOK Pros

  • Slimmer profile than quad rail
  • Removes weight of unused rail sections
  • Magpul backed and supported
  • Durable and reliable

M-LOK Cons

  • Requires extra tools to mount accessories
  • Somewhat technical to mount and dismount accessories

The Difference Between KeyMod and M-LOK

For years, both the KeyMod and M-LOK system were neck and neck for reliability and durability for use. However, the backing of Magpul behind M-LOK and a specific USSOCOM report established M-LOK as the best. The report that 100 percent of the time an M-LOK system with attachments was dropped, it kept the attachments mounted. On the other hand, the KeyMod system was only successful 33 percent of the time, keeping accessories mounted.

This does not mean that KeyMod designed rail system is flawed. This simply means that in this report, it did not perform as well as the M-LOK system. Ultimately, the decision is up to you. Your rifle usage and preferences trump pretty much everything. If the rail is effective for you, use it. The same goes for M-LOK. Use what fits your needs.

Rail Scales: The Best AR Accessories

If you’re in the market for a new AR-15 accessory to attach to your new rail system, Rail Scales offers a variety of attachments for your rifle. It’s no surprise that as you upgrade your rifle you want the best to improve your shooting performance, whether that be scales, a sight, or a hand stop. No matter what you need, shop Rail Scales online now to find the best AR accessories online.