While an AR-15 is a handy weapon, it’s much more practical and fun to shoot when you mount accessories to it. If you don’t want a Picatinny rail, you can choose between KeyMod vs MLok instead. Let’s dive in and see how these two rail systems stack up.
Our Recommendation – M-Lok vs KeyMod: Which Is Better?
On the surface, both KeyMod and M-Lok rail systems look virtually identical. They utilize a Picatinny Rail shape on the top and modular negative spaces on the sides and bottom.
Although the specifications may vary between both systems, they’re designed for the same purpose – to allow you to mount accessories.
However, when it comes to deciding the winner in a KeyMod vs MLok matchup, the US Naval Surface Warfare Center already did the legwork for us. This organization tests weapons systems for use in combat, and they’ve performed comprehensive tests on both rails.
Based mostly on drop tests, accuracy, and reliability, the M-Lok system outperformed KeyMod in almost every category. So, if you trust the US military to know which rail is best, there’s your answer.
However, we can’t just leave it at that. While M-Lok may be better suited for actual combat situations, is it optimal for gun enthusiasts? Let’s break down both rail system options beat by beat to see.
KeyMod System Overview
Depending on how you view the histories of KeyMod and M-Lok, this rail system was technically first. As a joint venture between VLTOR and Noveske, the idea was to make a standardized, open-source system that allowed engineers and shooters alike to develop upgrades so it would never be obsolete.
Although the KeyMod System had such lofty goals, it’s been struggling to reach them and outshine its main competitor, M-Lok. We have to admit that the KeyMod system is an improvement over traditional Picatinny rails, but it still doesn’t hold a candle to M-Lok.
Pros and Cons
- Pro: Super Lightweight Design – Whether you’re shooting at 100 yards or 500 yards, many variables can affect the accuracy of your shot. So, many individuals love KeyMod rails because they’re so lightweight. After installing a rail, you may not even know it’s there (or at least not feel it).
- Con: Not as Durable – A lighter frame may not bog down your shooting prowess, but it can lead to cracks and dislodged accessories. As we mentioned, the US Naval tests illustrated that KeyMod handguards couldn’t hold up to the scrutiny of actual combat missions. Civilian shooters may not experience significant issues, but they’re worth noting.
- Pro: Fast and Efficient Mounting – We’ll discuss how to install accessories on a KeyMod system, but the premise is super easy to master. You can mount attachments faster than you would with a standard Picatinny rail, all without adding extra weight.
- Con: Missing Accessories – Again, what can be viewed as a positive can also be spun into a negative. Although a fast mounting system is efficient upfront, it’s not as effective in the field. Plus, if you lose smaller parts (i.e., locking nuts), they’re hard to replace without getting a whole new accessory.
- Con: Unidirectional Attachment – Because of how the KeyMod system is designed, there’s only one way to mount and dismount an add-on. So, if you have to reposition the item, you need to install it into a different hole.
How to Mount KeyMod Accessories
The shape of the KeyMod rail system tells you exactly how to mount an attachment. The design works similarly to a front door chain with a wide hole on one side and a smaller hole on the other.
Mounting nuts hold the attachment in place, and you just have to tighten the nut to keep everything secure. However, as you might imagine, vibrations and heat can cause the nut to come loose over time. So, you’ll have to inspect your accessories regularly to ensure they’re not about to fall out.
History of the KeyMod Rail System
This rail system came out in 2012 as a joint venture between VLTOR and Noveske. VLTOR is a big name in weapon accessories, and Noveske is a high-end rifle manufacturer. So, this pairing made a lot of sense from a practical point of view.
Further enhancing KeyMod’s chances was the fact that the design was open-source, meaning engineers could tinker with and improve it without having to pay expensive licensing fees. Although the precursor to the modern M-Lok was already out in 2012, KeyMod’s simplistic design and backing from two major players gave it a distinct advantage coming out of the gate. (1)
M-Lok (aka Modular Lock) is produced by the company Magpul, and it has effectively changed the game when talking about accessory rail systems for rifles, especially the AR-15. Since the modern version came out in 2014, it has become the gold standard for mounting accessories to your weapon, and it doesn’t look like it’ll be dethroned anytime soon.
Pros and Cons
- Pro: Easy Adjustability – The secret of M-Lok’s design is the uniform holes on the sides of the handguard. Unlike KeyMod, the shape of the opening doesn’t change, so you can move your attachment to the front, back, or center of the hole. This flexibility means you can adjust your accessories without having to dismount and reattach them.
- Con: Hard to Detach – If you’re only using one accessory like a front handle or bipod, it’s pretty easy to get inside and loosen the T-nut. However, the more attachments you put on your gun, the harder it is to get them off.
- Pro: Better Stability – The US Navy tests illustrated that the M-Lok system only deviated by 1.3 MOA, while KeyMod shifted by 4.9. So, you can use your M-Lok over and over without having to readjust or re-tighten your scope to zero it out.
- Con: Not as Durable as a Picatinny – There aren’t many downsides to the M-Lok system, but one area where it falters against the OG is in durability. However, this disadvantage only matters during heavy-duty combat situations, so it shouldn’t matter for civilian uses like hunting or target practice.
- Pro: Abundant Accessories – Now that the M-Lok is becoming the gold standard, virtually all accessory manufacturers are building compatible items. Plus, you can attach Picatinny-style adapters to the negative spaces, meaning you get the best of both worlds.
How to Mount M-Lok Accessories
Each accessory comes with a T-nut that is long on each side. All you have to do is run the nut into the hole, turn it so the edges grip the sides of the hole, and then tighten the nut. When adjusting your accessory, you can just loosen the nut and slide the item back and forth without having to remove it entirely.
History of the M-Lok Rail System
So, the precursor to the modern M-Lok system was MOE. Magpul helped develop the Masada gun in 2007, and that design had a modular rail that made it easy to install attachments like scopes. Shortly thereafter, Magpul developed its MOE system, but it wasn’t quite as durable or reliable as M-Lok would become.
The modern M-Lok rail came out in 2014, and it’s backward compatible with MOE products. However, you can’t attach modern M-Lok accessories to an old MOE rail, so keep that in mind if you’re one of the few who uses that system.
KeyMod vs M-Lok: Does it Really Matter?
The short answer is yes, the features of both KeyMod and M-Lok rail systems do matter. While the differences are not as significant for civilian use as they would be for combat, they’re worth noting. Here’s a quick breakdown of the three main categories where these systems vary:
When compared to a Picatinny rail, neither the M-Lok nor KeyMod holds up. However, when comparing these systems to each other, the M-Lok has a distinct advantage. Stronger materials won’t crack or wear down after repeated use, and they maintain the structural integrity of the weapon.
Overall, KeyMod isn’t built for combat situations, while M-Lok is. So, if you want a military-style rail system, you should choose the one actually used by military divisions.
The M-Lok rail is lightweight, but not as much as KeyMod. Typically, the primary selling point of a KeyMod system is its lack of bulk, meaning you can fire and maneuver your weapon without affecting your shot too much.
However, lighter materials can break down, particularly if you accidentally drop your weapon. Also, vibrations can loosen accessories more easily over time, so there’s a bit of a trade-off.
That said, if you only use your AR-15 for occasional shooting, you shouldn’t have to worry about KeyMod’s shortcomings.
Although we’ve discussed both rail systems and their durability, strength refers to how well they can hold onto attachments.
Based on US Naval tests, KeyMod rails are much more likely to lose accessories compared to an M-Lok or Picatinny. The problem is the way KeyMod’s holes are designed. Even with a tightened nut, it can slip backward, causing the attachment to fall out by accident. (2)
KeyMod vs M-Lok vs Quad Rail
Technically, KeyMod and M-Lok are both “quad rails” because they have attachment points on all four sides. However, a traditional Quad Rail refers to a Picatinny “cheese grater” system on each side.
This design came out first (because Picatinny rails were first), and it allowed shooters to equip accessories on each side without needing to mount individual strips. Unfortunately, it also came with two downsides:
First, the Quad Rail had sharp edges, so shooters without gloves could wind up with cuts and scrapes on their hands. Second, the rail was quite heavy, so it was harder to maintain accuracy and consistency when shooting (particularly at longer distances).
So, M-Lok and KeyMod’s design with open-air holes on the sides and bottom of the handguard alleviated both of these issues. As we’ve discussed, the shape of these holes and the ruggedness of the materials differ between KeyMod and M-Lok, with the latter having a distinct edge.
M-lok vs Picatinny Rail System
Now that you understand a bit more between the KeyMod and M-Lok, we have an article on the differences between the M Lok vs Picatinny rail systems.
Coolest Free Float Handguards Out There
For more reading on specific brands, make sure to check out our post on the coolest free float handguards out there where we cover the best on the market today.
What is better: M-Lok vs KeyMod?
According to US Navy tests, M-Lok is better than KeyMod for durability, reliability, and performance. KeyMod accessories can come loose if a user drops or bumps their weapon, and the lightweight materials can crack under pressure.
Do people still use KeyMod?
Yes, many civilian shooters still use the KeyMod accessory rail because of its light frame and abundance of attachments. While it doesn’t hold up in real combat situations, it’s still excellent for personal use.
Does the military use KeyMod or M-Lok?
Thanks to the US Navy tests, the military uses M-Lok rails over KeyMod and prefers them even when compared to the original Picatinny rail. The M-Lok mounting system offers distinct advantages that the Picatinny doesn’t address.
Why did M-Lok beat KeyMod?
M-Lok beats KeyMod because it’s more durable, the accessories stay in place better, and you can reposition attachments easily by sliding them forward or backward. These advantages are why the M-Lok system is the preferred option for civilians and military units alike.
What rail system does the military use?
Some military weapons still use the traditional Picatinny rail system because of its durability, and the fact that many military-grade attachments were designed for this handguard. However, many newer weapons utilize the M-Lok accessory rail because it’s more versatile and easier to use.
Can you convert KeyMod to M-Lok?
Yes, you can convert the KeyMod system into a proxy M-Lok system instead by installing conversion attachments. However, these options are typically only recommended if you already have a KeyMod so you don’t have to buy a separate rail.
Is KeyMod any good?
Yes, KeyMod accessories are very handy and reliable, and the system itself is easy to master. As long as you’re not looking for a heavy-duty rail system, KeyMod will work great for civilian uses. However, if you’re new to firearms and want to start with a superior rail, we recommend upgrading to M-Lok instead.
Can you attach M-Lok to KeyMod?
Yes, you can attach M-Lok accessories to a KeyMod rail if you get the correct adapters. These pieces are available for purchase at many online stores, so they’re not hard to find or install.
- Cheaper Than Dirt, Fad or the Future, The KeyMod Rail System, retrieved from https://blog.cheaperthandirt.com/fad-future-keymod-rail-system/
- The Firearm Blog, MLOK Is Better And NSWC-Crane Has Proof, retrieved from https://www.thefirearmblog.com/blog/2017/05/08/mlok-better-nswc-crane-proof/
I have been writing firearms and outdoor material for over 50 years to date. I have hunted across the world, including Russia, and a great deal of time professional hunting in Australia. I currently live in the American West and hunt all across the Black Hills of South Dakota and the Big Horn Mountains. I have specialized much of my work as a load developer in shotguns and rifles. I have run a small company that builds suppressor barrels of my design and load tests for writing purposes and consulting. My commercial names include Ballistics Research & Development / Metro Gun Systems TM.
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