Remember Betamax? It was the early rival to the VHS videotape format, and at one time, just as popular. But if you were born after about 1980, there’s a good chance you’ve never even seen a Betamax tape.

We’re about to see a similar showdown play out in the world of rifle accessory rails. The picatinny accessory rail system has been the standard for bolting stuff to our AR-15s and other rifles for several years now. It’s an excellent system, especially for mounting optics, but including picatinny rails on a rifle’s foreend/handguard can add a lot of unwanted bulk and weight.

To alleviate this, there are low profile handguards that allow the user to attach small sections of rail only where they are needed. Not a bad solution, but what if we could eliminate the middle step and attach accessories directly to the handguard without the need for a picatinny adapter? The KeyMod and M-Lok systems do just that.

Keymod vs MLok picatinny adapter
Neither the KeyMod (right) nor M-Lok (left) systems are a replacement for the picatinny standard, but they complement it. Picatinny adapters like those above are the most common accessories for both systems.

The KeyMod System

Released in 2012, KeyMod was developed and released through a partnership between VLTOR and Noveske. It’s an open-source, public domain design, meaning that any company can make rails or accessories using the system without paying a dime in royalties.

Handguards built with the Keymod system can be incredibly lightweight, and allow for the direct attachment of any Keymod-compatible accessories. Several companies already produce Keymod rifles and handguards as well as attachments like vertical foregrips, bipod adapters, sling adapters, and flashlight mounts.

Keymod rails consist of rows of “keyholes”. To attach a keymod-compatible accessory, line up the lugs on the accessory with the round part of the keyhole. Slide it forward, and then tighten the screws.

Demo: Attaching a bipod mount to a Bravo Company KMR-13  KeyMod rail

The Magpul M-Lok System

Pretty cool idea, right? Well, Magpul thought so, too. They looked into making some Keymod-compatible accessories, but weren’t happy with the way the system worked with polymer attachments. So earlier this year, Magpul came up with their own competing standard called the M-Lok system. To increase their chances of this new standard taking off, Magpul has also made M-Lok free for other companies to use.

Magpul’s new M-Lok system uses slots in place of the keyholes. The attachment lugs on M-Lok accessories are t-shaped and bi-directional so they can be placed at the front or rear of the slots.

Demo: Attaching a flashlight mount to a Midwest Industries M-Lok rail

So now we’ve got two open-source direct-attachment rail system standards that are a little different but ultimately seek to address the same problem. Will the marketplace tolerate two standards? Or will one eventually dominate, leaving the other to become the forgotten Betamax of the AR world?


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  • Jacob Walters

    I think M-LOK will eventually win because it is easier and cheaper to manufacture.

    • John Daniels

      Also, for accessories that can be mounted facing either direction (like a VFG), you can’t accidentally mount a part backward and then have it randomly fall off later, as with Keymod.

      • spasmonaut

        That’s a very good point. I do believe that from the material I’ve reviewed through various sources that M-LOK is inherently more robust in that the manufacturing is far simpler than KeyMod, although I see the merits and positives to both and have no beef with KeyMod. That being said, M-LOK ultimately won me over and I haven’t regretted the transition from Picatinny to M-LOK on my carbine. My rifle still uses Picatinny but I don’t have the need to outfit it quite the way I have my carbine. Choice is great, and I welcome everyone to the table to feed us!

        • Just M.

          Hear hear, three cheers for capitalism, bringing us as many choices as the market will bear!

  • Chris Goldsmith

    I’m also on the m-lok side of the camp !!

  • Nathan Murr

    MLOK will win, it’s better in almost every way.

    • joe

      That’s what the Betamax people were saying. The best doesn’t always win.

  • Tanner Anders

    M-LOK also doesn’t look like big box store shelving.

    Just sayin’ 😉

  • Walter Small

    M-LOK is more adjustable and just as fast n easy.It looks a tad more rugged too.

  • Steve Culbertson

    since there are so many rifles already equipped with the picatinny rail system I don’t see either becoming mainstream for a long time. When I buy mounts etc. for my rifles I expect to see a choice between rail Key-mod or M-Lok adapters for a long time – the rifle manufacturers will likely play a big part in what wins out if any

  • John Daniels

    For all the reasons other posters have already stated, I’m reasonably sure M-LOK will win over the long run. I have one setup with Keymod, which I now regret. Future builds (including the one that’s currently in-progress) will all be with M-LOK.

    • Calvin

      Why do you regret getting Key-Mod? What didn’t you like about it?

  • John Markos

    +1 on the M-lok it gives nothing up to the Keymod in fact it’s better and is far more aesthetically pleasing.

  • Jeff Henry

    The surface area that the Keymod lugs mount to, compared the the M-LOK lugs, is greater therefore making it stronger. And with companies like Midwest Industries coming out with adapters for both systems, it really doesn’t matter which you pick, you’ll be able to use all the attachments and accessories.

  • Tony Yap

    A better comparison would have been Bluray vs HD-DVD. LOL. Either way I am still torn on which to get. I love everything Magpul and so I might get M-LOK. FWIW I chose HD-DVD and that didn’t turn out well 🙁

  • Cody Earnshaw

    Keymod is they way to go NOVESKE!!!

  • Magpul

    Just to clarify, we have nothing against Keymod. It’s use of a conical nut makes it unsuitable for non metal mount surfaces such as MOE handguard applications.

    M-LOK is effectively MOE 2.0 with direct attach capability allowing it to be used on longer freefloat rail systems with no backside access. The MOE slot system was introduced back in 2007 with the MOE handguards and M-LOK accessories are backwards compatible with older MOE handguards via a small adapter plate.

    To put things into perspective the MOE handguard and accessory market in 2014 was approximately 10 times the size of the entire Keymod market and it has remained the second most utilized handguard mounting system (second only to the Pictinnany rail) for the last 5 years.

    With M-LOK replacing every existing Magpul MOE slot handguard in 2014 and with the introduction of 4-6 new hand guards this year, M-LOK adoption in 2015 will remain several times the size of the entire Keymod marketplace -if used by Magpul alone.

    Rather than keep the system propriety (like MOE), M-LOK was released with full manufacturing TDP as a free license for all manufactures to utilize. M-LOK already has about 200 licensees signed up for it along with over 100 already released products and it is not even a year since the system was publicly announced.

    In short M-LOK does not depend on Keymod’s demise for it’s survival.

  • Tim Davis

    Isn’t the keymod mounting process sturdier? You tighten until tight, rather than pre-adjusting nuts and tightening with a quarter turn? It seems like keymod has less room for error and a more reliable tight mount. Correct me if I’m wrong.

    • No, the M-LOK requires more than a quarter turn (though I can see how you might think that based on the way the video was edited). The first quarter turn correctly orients the nut which catches on the other side of the handguard and then you continue turning until it’s tight.

  • Neither will win. The only advantage is reducing weight, but clearly Picatinny is used worldwide and accessories are everywhere. For the majority of people, Picatinny is just fine and will continue to be THE STANDARD 😉

    • ymom2

      You attach a Picatinny to your M-LOK. Now it is lighter and has Picatinny right where you want it.

      • DW

        I am having a custom handguard done, and will simply have picatinny rails of a selected length attached only where I want or need them. If I need more or different lengths attached I will simply buy more and drill a couple of holes to hold the rails. Problem solved.

  • An average Joe

    Neither of these are optimal. You’re screwing a thing onto your rifle so you can screw a thing onto your rifle. It’s ridiculous, and simply one more thing you have to watch out for, if it comes loose from vibration or even thermodynamic expansion and contraction, or wears out, or strips. If the front of your rifle is heavy, you have too much shit on it, and probably don’t need rails anyways, and should be looking at polymer handguards, or even just using the normal clamshell handguard.

  • Trent G

    I prefer the M-Lok over the KeyMod attachment is easy on both but the idea of my rifle covered in little penis shapes is not appealing.

    • Tim

      If you are seriously that concerned about those holes looking like a “penis”… my guess is that your penis could fit through those holes.

  • Rusty Shackleford

    I think its more of a matter of preference. M-LOK looks more aesthetic than having a bunch of tiny dicks covering my rail.
    Ultimately, the big irony is that most people screwing a pic rail onto it so you can screw an accessory onto that.

    • R0CKnU

      I totally agree. The whole point of M-LOK for me is to attach any new I buy stuff directly to the rail. But those pic rails are for backwards compatibility with my old stuff and I’m really grateful for the option. I still prefer short rails, where I want them, over a fixed quad. It may not be perfect but at least it lets me use what I have until I can afford to replace it.

  • Aaron

    I don’t have either. What I do have is the Daniel Defense MFR (v7) rail which uses rail attachments very similar to the Mlok (T-nuts). However, the original DD MFR (v7) rail set up isn’t as position flexable as the Mlok since it uses small holes like the Keymod and still have to use picatinny attachments to attach most accessories with out modifications. As far as looks, Mlok looks cleaner another thing about the Keymod is that it’s basically based off the same concept as “wall mount” holes. You know, when ever you go to hand up wall art, devices or clocks, etc. and then just tightening down the screw. I’ve never really used a keymod but it seems that it’s possible that what ever attachment could slide out to the entry/exit opening of the Keymod hole if hit or pulled hard enough. ?? I don’t know that’s just my concern with it.

  • tophat1234

    Colt Canada’s new MRR will be using M lok. Not sure how significant that is though.

  • Charles Saboteur Rahten

    I love my keymod and I’m not knocking magpul. They make alot of great stuff. Like the zhukov stock, they nailed that! Though bcm nailed the kmr rail! This thing is awesome all the way around. It looks great, handles great, attachments are heavy duty and simple to attach. Cover up the part of the rails you ain’t using with their rail covers and presto! The thing is sharp. Price is high but I’m not regretting it.

  • Jakewwa

    Why not just have a bunch of rows with screw holes?? That’s all you need!

    The only thing attaching the keymod/mlok are the screws. At the other end of those screws are lugs, which could just be the rail itself. So all you need are screw holes.

    Maybe the rail would need to be thicker where the rows are.

    Think a thicker row of metal might add too much weight? Just think about the weight you are adding by adding the redundant picatinny rail to the handguard to attach your accessory.

    I’m saying the intermediate picatinny rail is unnecessary.

    Make your accessories direct attached!

    • Todd Johnson

      The major problem I see with screws is they will eventually strip out, rendering that spot on the rail useless. Screw threads cannot match the torque that clamps provide.

  • The video fades out after the first 1/4 turn, but that does not imply that more tightening is not necessary. It’s really not that difficult to figure out if you actually have one in your hands.

    • Magpul

      The M-LOK installation FAQ clearly explains the first quarter turn positions the nut and further turning locks the accessory down according to the published torque specs-

      • For attaching metal accessories to metal hand guards: 35 in/lbs
      • For attaching polymer or metal accessories to polymer hand guards: 15 in/lbs
      • For attaching polymer accessories to metal hand guards: 15 in/lbs

  • Magpul

    Hi Lance, Your engineering assumptions are not correct. The M-LOK system uses a larger bolt and has more direct surface engagement than keymod resulting is much greater torque being able to be applied to M-LOK along with greater pull out strength than keymod. Keymod’s issue with plastic and carbon fiber comes from the conical nut surface applying force at a 45 degree angle promoting deformation or cracking in non metal mount applications such as MOE handguards.

  • Michael Romano

    Funny how there has been an absolute explosion in front rails and front-rail accessories as manufacturers have figured out how to sell more and more junk Chinese tacticool accessories to weekend “Soldiers of Fortune.”