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Everyone loves accessories, and shooters are no different. Accessories mean extra stuff, and when it comes to stuff, it’s a more-is-more world. Proof of this when it comes to modern firearms is that more and more guns these days are festooned with accessories. But how do all of those lights, lasers, bipods, and bubble levels stay on a gun? Well, that’s where KeyMod vs M-LOK comes in.

KeyMod and M-LOK are two of the most effective and popular platforms for attaching accessories to a firearm. They both work great, but there are important differences between the two. Here’s a guide to KeyMod vs M-LOK and the answer to which one is better for you.

Table of Contents

  • Where did KeyMod and M-LOK come from?
  • What is KeyMod?
  • What is M-LOK?
  • KeyMod vs. M-LOK: Which is better?
  • KeyMod vs. M-LOK: Which is right for you?

Where Did KeyMod and M-LOK come from?

photo of a Picatinny rail on a Ruger American
The Picatinny rail, like this one on a Ruger American rifle, was originally developed by the military in the 1980s. Matthew Every

Years ago, if you wanted to put a flashlight on your gun, you needed to find a gunsmith or break out a roll of duct tape. But a lot has changed. In the late 1980s, the military developed a standardized rail for mounting gun accessories called the Picatinny rail, which most shooters are very familiar with these days. If you’ve mounted a scope to a modern hunting rifle, you’ve likely used Picatinny rail, as it’s become an industry standard on a lot of newer rifles.

But having a long Picatinny rail on your gun all the time has its drawbacks. Pic rails can be heavy, bulky, and abrasive on bare hands. That’s why, in the mid-2010s, two companies developed systems to allow a shooter to add and remove sections of Picatinny rail only where they wanted it, or mount accessories without using Picatinny rails at all. The two systems are called KeyMod and M-LOK.

What is KeyMod?

photo of a rifle with a rail attached via the keymod system
A section of Picatinny rail mounted to a KeyMod forend. Matthew Every

The KeyMod system was invented in 2010 by VLTOR Weapon Systems and Noveske. Its commonly found on the forends on AR-15s and AK-pattern rifles. VLTOR and Noveske designed the system to give a user flexibility in terms of what kinds of accessories they want to attach to a gun and where. They made the system open source so any company could produce it.  

Keymod rails are covered in keyhole-shaped slots in a uniform pattern. Each hole has a larger end and a smaller end. To attach an accessory or rail, you place studs (which comes with KeyMod-compatible accessories) in the larger hole, slide the accessory forward, and screw it into place. The studs lock the accessory or rail to the KeyMod forend, and when properly installed, it will not move under recoil.

What is M-LOK?

a section of rail attached via the M-Lok mounting system
A section of Picatinny rail mounted to an M-LOK forend. Matthew Every

M-LOK was developed by Magpul in 2014. Similar to KeyMod, M-LOK uses slots to attach accessories and rail sections. Today, M-LOK is more common than KeyMod, and it can be found on tactical rifles, hunting rifles, and a number of other firearms. Magpul invented M-LOK because they found it difficult to attach non-metal accessories to KeyMod. M-LOK is not open source, but manufacturers can get a free license to produce it from Magpul as long as they follow the correct specs. M-LOK accessories use T-nuts to go through the rail’s slots. Once through, the T-nuts need to be rotated 90 degrees and then tightened, and, like KeyMod studs, they lock the accessory or rail section in place so it will not move under recoil.

KeyMod vs. M-LOK: Which Is Better?

As to the question of which is better, the United States Special Operations Command (SOCOM) had wondered exactly that in 2016. They bought a variety of off-the-shelf KeyMod and M-LOK rails, mounted up a bunch of accessories, and put them to the test. SOCOM conducted endurance and rough-handling tests, repeatability (for things like lasers) tests, and a drop test.

Both KeyMod and M-LOK passed the endurance and rough-handling test. But, during the drop test, SOCOM found a clear winner. M-LOK held its accessories 100 percent of the time while KeyMod only held on 33 percent of the time. M-LOK was also found to be more repeatable, resulting in smaller point-of-impact shifts than KeyMod for aiming devices like lasers. In the end, SOCOM went with M-LOK, so as far as they are concerned, it’s better.

KeyMod vs. M-LOK: Which Is Right for You?

photo of the forend of a hunting rifle with Mlok slots
This row of M-LOK slots has been milled into the stock of a Springfield Model 2020 for mounting a bipod. Many modern hunting rifles now have them. Matthew Every

Just because KeyMod didn’t win the SOCOM test doesn’t mean you shouldn’t buy a KeyMod rail. Personally, I find it a little easier to work with than M-LOK. It may not be as strong as M-LOK, but when was the last time you jumped out of a helicopter or stormed a beach? If your answer to that is a few weeks ago, then you should go with M-LOK. In the future, you might not have much of a choice, either. The way things are going, M-LOK is becoming way more popular than KeyMod.

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Almost every cutting-edge hunting rifle today has a little M-LOK tucked into it somewhere, and that’s a good thing. Predator hunters and hog hunters—or anyone else who uses a gun at night—have great low-profile options for mounting a flashlight. And hunters who use bipods will find that M-LOK is more user-friendly than attaching a bi-pod to a sling swivel. Whichever you choose, try not to get too carried away with add-ons. I know, it’s tough. More is more, after all. But if you go too far, your rifle may be most effective as a boat anchor.