5 SLOT PICATINNY M-LOK RAIL SECTION. SKU: MLRS1 Weight: 0.56 Ounces Shipping: Calculated at Checkout. Current Stock: Quantity. Both the KeyMod and M-Lok systems support direct attachment of optics, lasers, flashlights, bipods, and other accessories to a negative space mounting point. In other words, M-Lok and KeyMod both have integrated openings machined directly into the hand guard. Compatible accessories can be mounted to a bracket that locks into those openings. Midwest Industries, Inc. Manufacturer of quality tactical rifle accessories for the AR15/M16, AK47/74, Ruger SR-22, Ruger 10/22 and many others. The Modular Lock, or M-LOK, system ditches the keyhole shape in favor of slots and benefits from attachment lugs on accessories that are t-shaped and bi-directional. This design allows M-LOK.

We were asked, “What are the pros and cons of M-Lok vs Keymod?”

Long ago there was no standard for attaching stuff to firearms. We use sling studs, bayonet lugs, hose clamps, bespoke custom mounts, etc.

Then came the MIL-STD-1913 Picatinny rail. And all was well. It took some time for people to move away from the weaver rail, but eventually most of the world adopted the 1913 rail. Except for Zee Germans, who as always thought they could do better. They came up with their own spec for rails, where they took the surface most likely to get damaged in use and make that the critical dimension. Thus the NATO spec rail was born.

Then people wanted smaller and slicker hand guards. Companies started milling off the rail section and offering bolt on rail sections. But each company had their own system. While the bolt spacing was somewhat standardized due to the sizing of Picatinny rail, how the rail section interfaced was not standardized. KAC, LMT, Larue, Colt, etc all had their own various rail attachments for their slick handguard.

VLTOR designed a new mounting system in 2012. Somewhat similar to the old post and slot system used in shelving, they included a taper on the mounting tab and recoil lugs. Best part is that they released the design as open source, so any company could use it for free.

Noveske and Bravo Company were early adopters and helped popularize the system. It looked like it was going to be the next standard. But then something interesting happened.

Before we get to what happened, lets talk about the other option, M-LOK.

Magpul came up with a new mounting system on their Masada and their early MOE line of accessories. They had slots cut(or molded) into the hand guards allowing accessories to be bolted to the slots. This was 2009. But this MOE slots sucked. They were inconsistent, and the backside of the slot had to be accessed to install an accessory.

In 2014, Magpul came up with a new standard, the M-LOK. M-LOK used slots where the accessory would lock in using a rotating T-Nut. M-LOK is free licensed, not open source like KeyMod. So people can made it freely, but they have to get permission from Magpul. This way Magpul ensures people don’t deviate from spec.

Wow, writing the history there took longer than I thought this article would be.

So what are the cons:

KeyMod accessories can be installed wrong. When I first mounted a KeyMod QD swivel, the next day I read about people mounting Keymod accessories backwards. I said, “How could anyone mount one of these backwards?” Then I found out that I mounted mine backwards. Doh.

Also some companies are cutting corners and making KeyMod accessories out of spec. Either missing the critical taper on the lugs, or missing recoil lugs.

As for M-LOK. M-LOK accessories protrude into the rail, so in areas with little clearances they can be an issue. Or sometimes the screws can protrude enough to touch a barrel in a narrow free float tube.

It looked like KeyMod was winning the modular handguard war. Many were pushing it as the superior mounting system and it looked like the Army was going to adopt it for use on newer hand guards and sniper rifles.

Then we get to the interesting test. NSWC-Crane did a test between the two. They deemed M-LOK as being better.

Overall, test and evaluation demonstrated that the M-LOKTM modular rail system surpassed the performance results achieved by other modular rail systems. In repeatability testing, M-LOKTM allowed for the repeated installation of the same accessory rail in the same location on a handguard with an average point of aim (POA) shift of 1.3 MOA, as low as one quarter the average POA shift observed by other modular rail systems. Drop test results demonstrated that M-LOKTM systems maintain securement of accessories to the handguard and sustain less damage from impact forces than some other modular rail systems. Failure load testing demonstrated that M-LOKTM systems support the highest load of all modular rail systems tested. In fact, the test equipment used to interface with 1913 accessory rails secured with the respective modular rail system across testing repeatedly failed prior to failure of the M-LOKTM attachment system. Even so, testing of the M-LOKTM systems failed at loads as high as over three times the maximum failure load of some other modular rail systems. NSWC Crane recommended to USSOCOM that the M-LOKTM modular rail system be utilized over the alternative systems tested. USSOCOM has chosen to incorporate the M-LOKTM modular rail system in acquisition efforts including the Suppressed Upper Receiver Group (SURG) and Advanced Sniper Rifle (ASR).

Since this test, interest in KeyMod has been reduced, but it is far from dead. M-LOK is gaining much more popularity.

M-LOK design of just being simple slots has allowed M-LOK mounting slots to be added to a great deal of accessories for other older firearms. Newer gun designs are able to have thin aluminum hand guards with simple slots milled in them allowing for the end user to add what ever accessories they deem fit.

Both are good, but now the consensus is that M-LOK is better.

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.

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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

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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.

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

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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?