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KeyMod vs M-LOK: Military Chooses The Winner

Find out the clear winner in KeyMod vs M-LOK. Plus our favorite handguards for each kind of attachment system.

One of the best parts about owning a rifle is being able to play with all of the cool attachments.  

A good optic sight, flashlight, or bi-pod can really help you to get more out of shooting your rifle – but first you’ve gotta mount them.

The standard mounting system on most rifles, especially those on the AR-15 platform, has been the Picatinny rail.  In fact, it still is one of the most widely used mounting systems because of its, straightforward, easy-to-use nature.  

FN 15 quad rail
FN 15 Quad Rail

But the problem with the Picatinny system is that it can add unnecessary weight to your rifle and bulk it up in a bad way, especially when placed on the fore end of your rifle.  

From this inconvenience came two new ways to mount gadgets to your AR-15 (or other rifles!): the KeyMod and the M-LOK.  Both of these mounting systems promised to cut back on weight while providing a wider range of mounting options.  

Lucky Gunner M-LOK Vs. KeyMod
M-LOK (left) and KeyMod (right), Image courtesy of Lucky Gunner

Even better, both of these systems also gave gun owners the opportunity to mount small rails directly to their handguards, effectively eliminating the need to attach a large Picatinny rail across the gun.  The benefits of these two systems were revolutionary.  

Now that you’re able to stick rails adapters only to the part of the gun we plan on mounting an attachment, you don’t have to worry about unnecessary weight or that cheese grater, snagging sensation of your Picatinny rail ripping across your hand, clothing, or rifle case.

If you just want to know…here’s our picks for the Best AR-15 Handguards out there.

What’s the Better Choice between the Two?

Lots of AR-15 Uppers
Lots of AR-15 Uppers

As you probably already know, two similar items in the firearms community cannot exist without being fiercely compared with each other.  So naturally as the KeyMod and M-LOK systems grew in popularity, hobbyists and experts began debating over which system is better.

Today, we’re going to take a look at both mounting systems and see how they’re similar and how they differ.  

The KeyMod

The KeyMod Logo and Iconic Keyhole Slot Design

The KeyMod system gets its name from the shape of the slots, which look like old-fashioned keyholes.  The idea here is that you put the lug through the big circular opening and then slide the attachment forward, tightening the Allan wrench in the narrow part of the slot until your attachment is securely fastened.  

KeyMod’s design is completely open source, so anyone who’s interested in manufacturing products using the KeyMod system can do so without having to pay royalties.

AR with KeyMod Rail
AR with KeyMod Rail

The Good: Mounting accessories require little to no special attention thanks to KeyMod’s self-aligning design.

The Bad: KeyMod doesn’t have nearly the industry support as M-LOK, which is backed by industry titan Magpul, who exclusively makes M-LOK-compatible systems.

Notable Mentions

KMR Series KeyMod Free Float Handguard by Bravo Company

Available Coupons

The KMR series will cut some bulk off your rifle and give it a slimmer profile, creating an overall nice look.  Another benefit of Bravo Company’s KMR series is that they feel much smoother in the hand than some of the other KeyMod systems out there.

UTG PRO KeyMod Super Slim by Leapers

at OpticsPlanet

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

The Super Slim handguard removes some fluff from your handguard while giving you a sturdy, 112-KeyMod slot design.  And with more than ten different color combinations, finding one that fits your personality and style shouldn’t be a problem.

The M-LOK (Modular Lock)

M-LOK Logo
M-Lok by Magpul

Unlike KeyMod, the M-LOK system doesn’t have a keyhole shape to slip your bolt into.  Instead, the system is made up of narrow slots that T-shaped nut that, when turned, lays across the slot, locking the attachment into place.

Magpul, the company that helped come up with the M-LOK system, decided not to make their product open source.  Instead, they chose to offer free licensing to any manufacturer that obtains permission ahead of time.  The reason for this is to ensure that every M-LOK system is made with the same quality and design as the original.


The Good: You can mount your attachment to the front or rear end of the slot, as opposed to only mounting on the rear, narrow part of the KeyMod.  Also, most Magpul accessories can mount directly to the M-LOK system without needing a rail adaptor.

The Bad: You have to be more careful making sure your attachments are properly aligned when mounting them to your M-LOK device.

Notable Mentions

MOE M-LOK Handguard by Magpul

at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

It’s one of the most affordable handguards on the market.  It’s perfect for the shooter looking for a basic, minimalist design that doesn’t intend on mounting anything too excessive.

G3M Series M-LOK Handguard by Midwest Industries

at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

The G3M Series is an aggressive handguard with ample mounting slots to handle whatever you’re planning on attaching.  It’s also a lightweight handguard that sits comfortably in the hand (no grab) and is made from a durable material that can handle whatever you throw at it – which is why it comes with a lifetime warranty.  

The Nail in the Coffin

For the longest time, it looked like KeyMod and M-LOK were neck and neck in the race to market domination.  While the M-LOK had the backing of Magpul, which was huge news, it still wasn’t able to do anything that the KeyMod could not.

And then US SOCOM tested both systems and released a report on their performance, and the news wasn’t so great for KeyMod.  

M-LOK in the Field
M-LOK in the Field

For most of the duration of the test, KeyMod and M-LOK both performed well.  

But when it came to stress testing the two systems, M-LOK rifles could be dropped on the ground and 100% of the time, the attachments would stay securely fastened to the gun.  For KeyMod, however, the success rate was a measly 33%.

The Verdict

The winner of this contest is clearly M-LOK.  In fact, the M-LOK system has approximately 3x the industry support as KeyMod.  But, while that SOCOM report didn’t do KeyMod any favors, the company hasn’t backed out just yet.  After all, most of us aren’t putting our rifles through SOCOM levels of stress.

BCM Recce-16, Running
BCM Recce-16, Running

What Are You Rocking?

While there’s no reason to believe M-LOK wouldn’t come out the victor in this battle, that doesn’t mean that KeyMod handguards are inherently flawed.  As long as you’re not in a situation where you’re going to be running, gunnin’, and clanging your rifle against the ground and everything else, you probably won’t be put in a situation where your attachments loosen or fall off anyways.

PSA AR-10 Gen 3 Upper and Lower
PSA AR-10 Gen 3 Upper and Lower

Remember, if you’re looking for a good handguard for your rifle, go with something that feels like good quality, regardless of the name on the package.  For the average shooter, that’s far more important than whether it’s an M-LOK or KeyMod.  

In fact, some of my favorite handguards are the KMR handguards made by Bravo Company.  They’re sturdy, lightweight, and have a nice, solid feel to them.  

Rifle with Bravo Company KMR Handguard
Rifle with Bravo Company KMR Handguard

Now be sure to tell us what you’re rocking on your tactical builds.  Do you like the KeyMod or the M-LOK system?

And if you’re in the market for some new handguards for your AR-15, don’t forget to check out our recent Handguard Roundup. There you’ll be able to find a lot of cool and unique handguards for your gun. Also check out our explanation of Weaver vs. Picatinny Rails.

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23 Leave a Reply

  • Commenter Avatar

    What I want to know if I have key lol can I put on a m lok system rail and will the bolts fit and hold are they interchangeable

    April 9, 2022 6:35 am
  • Commenter Avatar
    Sam M.

    A few builds ago, when most stuff was still Quad-rail, and I was checking out the various options, I leaned toward the key mod system; but when I wound up getting a pre-built upper that was M lock I went with it by default. While it can be true that M-Loc can be more difficult to mount especially without removing the handguard, I haven't had that much problem with it, but I don't usually put a lot of stuff on my rifles anyway. Since I started off with M-Loc, and already have some attachments for it, I will probably stick to M-Loc. I just recently got a PSA KS-47 with factory M-Loc free float handguard, and I'm fairly happy with it.

    With the old Quad rail setup, I had to cover the excess rail space with rubber covers, and while it worked very well, it did result in a large diameter on the fore end, as well as some excess weight; not a lot to be sure, but every ounce adds up. Also, while it was nice and grippy, and resistant to dings (Being a VERY sturdy setup) it just made the front of the rifle feel a bit too heavy and clumsy compared to a more current slim free float handguard. So, while I still think both Key-Mod, and M-Loc are viable platforms for me; I'll stick with M-Loc just to avoid having two different and incompatible systems. Now, if someone managed to come up with a line of quality accessories that would work for both systems; I'd be all for that, since if I came across a nice deal on an upper that had either one, I wouldn't have to be concerned about buying attachments in a different system, that I already had in the other.

    December 28, 2021 12:51 pm
  • Commenter Avatar

    I’ll stick to my KAC 12.5” URX II… I was blessed by God with large hands, so it’s girth doesn’t bother me. However, it’s nice that they are making slim handguards now for men with small hands.

    August 9, 2021 6:58 am
    • Commenter Avatar

      Some of have arthritis, especially those who have worked hard for a living. The slim profile is thus less painful and easier to grip.
      Bottom line: It's great that commercial manufacturers, thanks to capitalism, have built a wide variety of shapes and sizes to put an AR comfortably in almost any hands that want one.
      -Unlike the 1 size fits all carbine grip the army puts in every hand.

      October 13, 2021 11:47 pm
  • Commenter Avatar

    su xiaodong
    I like my quad rail. A 1/4 pound of weight or whatever it weighs over the others isnt going to slow me down. Plus I don't like the entire barrel covered. I can put anything anywhere and adjustment or removal is a breeze.

    August 8, 2021 11:35 pm
  • Commenter Avatar

    I like my quad rail. A 1/4 pound of weight or whatever it weighs over the others isnt going to slow me down. Plus I don't like the entire barrel covered. I can put anything anywhere and adjustment or removal is a breeze.

    August 8, 2021 11:34 pm
  • Commenter Avatar
    Jim Biasella

    I like my quad rail. A 1/4 pound of weight or whatever it weighs over the others isnt going to slow me down. Plus I don't like the entire barrel covered. I can put anything anywhere and adjustment or removal is a breeze.

    June 25, 2021 11:09 pm
  • Commenter Avatar
    Chaud Caliente

    I use M-Lok but I *LIKE* the KeyMod design better. Because I have been using Magpul accessories for a long time though, all of my forends are M-Lok. It's OK once the rail or accessory is mounted, but most of the time you must remove the forend so that you can hold the "nut" onto the backside while you tighten the screws. With KeyMod you don't have to do that which is why if I had to do it all over again, I'd go KeyMod.

    May 25, 2021 7:18 pm
  • Commenter Avatar

    I like the Key-Mod better as you can mount just about anything with out any issues. M-Lok in some cases you have to remove the hand guard to mount some rails or other attachments? There are very few attachments that have the nuts that fit into the forend to mount by just turning the nut about 25% to put tension on it. If you want a piece off rail or other attachment on your key-mod you basically put the rail together loosely and then slide it into the key-mod holes and tighten and much easier to mount attachments. Sorry didnt have my glasses and could only read some of the article so forgive me if you covered what points in it? hehe But i have found you at times may have to remove the forend to get some attachment's on your rifle.... I have all my ARs set up from 5.56s to 7.62x39 and 6.5Grendels and Valkaries. The only one im waiting on parts or i shoudl say accessories to finish on is the most expensive AR carbine i own. Its a spikes tactical lower/upper with Odin Works forend as well as grip,with a VG6 comp and Faxon 16" SS heavy barrel. it also came with a sight mark reflex sight on it. I only need back up sights and quick detach sling swivels for it and the gun is ready for work/play/varmints in the garden. Yeah 9mm is a big heavy but i always make rabbit or other varmints into stew anyway! lol I just recently made several new long gun purchases because my Blue state has already made it as costly and time consuming as they can to get pistol permits in our state with at least a 2 to 3month process. So i have been just puchasing more and more ,long guns then anything. Recently a Hatsan clone of that 22LR CZ bolt gun.For 219 and it is a great shooter for way less and a mossberg patriot super bantam chambered in 7mm-08 the forgotten caliber! 5R button rifled with a recessed target crown and adjustable butstock with extra spaces and a factory installed 3x9x40 and the total was right around 400.99 and its an awesome shooter! I got it for a bush gun for hogs and varmints but it turned out to be a very accurate rifle i could use for target shooting in local competitions in our gun club system! hehehe already looking into getting a boyds stock to replace the plastic one its in now.....sorry poly! lol I really wanted a .45Cal "other" firearm as we here in N.J. cant have AR pistols. In any case i ran out with abut 1400.00 bucks in my pocket and was panic shopping when i did purchase this 9mm carbine because nobody had a shorter barreled "other" firearm. But i love what i ended up with so that great! alls well that ends well! Now i just need a Marlin,Henry level gun chambered in .357mag/38Spcl! i would be happy with that for a while as my last purchase. Since i have already owned a 38Spcl +P and stocked up i would have ammo if i cant get .357 any where for now. that and my revolver would make for a good pair of bugout guns. Although i would have to carry another long gun or two for job specific tasks as well as as many other handguns i can carry hehe. GOOD LUCK ALL we are going to need it over the next few years! GOD BLESS!

    February 28, 2021 5:51 pm
  • Commenter Avatar

    The author overstates the Keymod "failures". The drops were 5feet, on to a steel plate, on to a steel plate, and there 6 drops, with six different orientations. While that might be relevant to SOCOM troops on a.deployment where logistical support might be minimal, its got.no relevance to the rest of the end users, who won't come within a fraction of use/abuse that might be subjected on a rifle by the SOCOM folks.

    The truth is anyone, other than that very small segment of end users, who is concerned over this, is stressing over a theoretical limit they won't ever come.close to approaching..

    I've got MLOK rails on my guns, but only because when I decided to change from the old cheese graters I got a good deal on MLOK rails. However, if I had Key mod, I'd be very happy with that too, knowing it works just fine for all but those folks in SOCOM.

    I'm sure the tactical Timmy's who have Keymod rails are pulling the " operator" beards out over this, but it's much ado about nothing.

    November 1, 2020 4:02 pm
  • Commenter Avatar
    Kalashnikov Dude

    I always rock the underdog. AMD PC's, and KeyMod hand guards. Chevy Trucks. I beat the hell out of all em. Maybe SOCOM was just doing it wrong, or more probably, was biased from the git go. Because I never had the trouble this article describes with KeyMod.

    October 13, 2020 8:24 am
  • Commenter Avatar
    Dennis D

    I have both, but prefer the MLOK. First: Magpul, Second: Occasionally, KeyMod tends to snad my finger on the taper of the keyhole.

    Way back when, I also preferred cassettes over 8-track!

    July 27, 2019 3:09 pm
  • Commenter Avatar

    I have both, I like both. My AR's aren't all tacticool, an occasional foregrip is about all I put on my AR's. I like the thin feel of either one, a quad rail is horrible, especially with covers.

    March 25, 2019 5:39 pm
  • Commenter Avatar
    Michael Kincaid

    Shoot what you have and spend money on ammo to train. If it comes down to buying a new rail or gun; I would go with the M-Lok because they are generally the same price.

    December 13, 2018 4:36 pm
  • Commenter Avatar

    Mine came with a Keymod rail and I’ve never bothered to switch it with an Mlok rail so keymod is what I’m rocking! I don’t plan on mounting much to the rail most I will do is a grip and a flashlight

    November 18, 2018 8:40 am
  • Commenter Avatar

    I have both, and neither has failed. I did notice that fewer manufacturers are making keymod accessories, which is a little annoying. I think keymod is the more attractive looking out of the two, even when paired with other magpul furniture.

    November 15, 2018 6:28 am
  • Commenter Avatar
    Steven Kraus

    I have had a Bcm Kmr keymid upper pretty much since they came out. Iv never had a problem of anything coming loose. Of course if never dropped my rifle either. That being said if I were to buy a new upper I would go with the Mlok just because of SOCOM's testing. Really either is a good system which should the civilian market very well

    June 20, 2018 8:26 am
  • Commenter Avatar

    Can anyone tell me the name of the handguard shown in the first picture? Pure beauty!

    April 19, 2018 10:02 am
  • Commenter Avatar

    I have three M-Lok MK4 rails by Geissele.I really like the quality & versatility of them. Look great too. Just bought another one taking advantage of the :Black Friday" deals at Brownell's. The extra 10% off put it lower than buying direct from Geissele during their own "Black Friday" sale.

    November 24, 2017 12:47 am
  • Commenter Avatar
    Jim M.

    I have the KMR on a light-weight build and I love it. In hand, it feels holding a skeleton .22 rifle compared to my Magpul furnished LE6920. Conversely, the Magpul Mlok hand guard has that old school basic training M16 feel, which I also love. Both have their place. Great article.

    November 3, 2017 3:01 am
    • Commenter Avatar
      Eric Hung

      Thanks Jim!!

      November 7, 2017 5:21 pm
  • Commenter Avatar

    I still like picatinny but they are indeed heavier. We have one rifle with keymod and have never had a problem. Yet to procure a rifle with M-Lok

    November 2, 2017 4:29 pm
  • Commenter Avatar
    Kevin Hagus

    My first handguard was a KeyMod system and that is what I have stuck with. It works great for me and I've never had a problem with any of my KeyMod accessories coming loose. By the time that M-Lock came along, I already had quite a few KeyMod rails and direct KeyMod accessories that mount directly to the KeyMod attach points. I'm not spending a whole bunch of money to switch to another attachment system when I've had zero problems with my KeyMod accessories.

    November 2, 2017 4:07 pm
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