MLOK vs Keymod is the topic of today’s article. Like many other internet slap fights I expect most will look at this like Ford vs Chevy. Different strokes for different folks. However, there are some differences between the two designs and the amount of support they have. We’ll talk about some of those differences and some anecdotal stuff this author has seen when using the two different systems. If you’re after a clear winner I think you’re in for a disappointment but if you want to delve a bit deeper into which systems have which advantages, keep reading!
MLOK vs Keymod
Chronologically, keymod has been around longer than MLOK. Who came up with Keymod is something for the internet experts to hash out on forums with tin foil. VLTOR weapon systems appear to be the ones who wrote the idea down and released the schematics in an attempt to proliferate a “standard” system for attaching rails and accessories. They openly admit Accuracy International was working on a similar design called Keyslot about the same time. The guys at VLTOR also note that it’s hard to take credit for a design that’s been around forever in terms of warehouse shelving and similar storage solutions. They just weaponized it!
Keymod rails and accessories utilize a similar keyhole shape design. The small end of the keyhole is forward towards the muzzle. Two special nuts with a taper fit into the keymod slot on the bottom of the rail or accessory. Then the whole rail or accessory is pushed forward in the opposite direction of recoil and tightened down. The idea is that recoil will only keep it in place. The static friction from clamping the tapered nuts against the inside of the rail keeps it from wobbling around. At least in theory.
MLOK on the other hand is something coming from the folks at Magpul. MLOK uses two special T Nuts on the bottom of rails and accessories. You slip the rail into the MLOK slot, then with a flick of the wrist you can clamp the accessory down. As you twist the allen wrench, the T nut rotates from being inline with the slot to being perpendicular with the T spanning the slot on the inside of the rail. As the nut tightens up, it grabs the inside of the rail to keep everything from wobbling around. Just as with Keymod, MLOK rails have small lugs that prevent the rail for moving forward and back. The difference here is that MLOK has a small lug beneath each bolt and typically a third lug if the rail or accessory is long enough to prevent movement under recoil.
MLOK bears quite a few similarities to a system Seekins Precision was using years ago that also used a T Nut and Slot design. There were no recoil lugs on the Seekins version though. It relied on pressure between the bottom and sides of the T Nut against the slots when tightened down. However, with the growing popularity of Keymod and later MLOK, Seekins just began producing rails using both mounting systems and abandoned their proprietary system. Which is kind of a shame because it was pretty handy and I don’t think I ever had a rail loosen up!
MLOK vs Keymod Issues
So which is better, right? I think they’re both really good. I also think they’re probably both going to continue just like Apple and Google offer competing systems for smart phones. MLOK is backed by Magpul since it’s their system. There’s a huge distribution network in place and you’re likely to see MLOK stuff where ever you see Magpul products sold. Magpul has been phasing out their older MOE mounting system which was a real pain to work with. Keymod on the other hand is being backed by Bravo Company who are producing a number of accessories for the Keymod mounting system. Accuracy International also uses a Keyslot that looks just like Keymod. I’ve heard Keymod will work with newer AI rails and I’ve heard it won’t with older ones. I can’t say for sure till I get my hands on a new AX stock.
However, with how well both systems work, I wouldn’t let either dissuade me from a purchase. I’d look at two things when considering MLOK vs Keymod. Are the accessories I want available in the system I’m planning to choose? I’d also look at which system has a wider array of products available. I believe MLOK has the edge there. I’ll point out one thing a lot of folks don’t think of ahead of time. The differences can be viewed as moot when you consider heat transfer from the handguard of the weapon to your hand. On a precision rifle the rate of fire is low enough that you could go with either system and direct mount accessories to the handguard with no issues.
However on a Carbine or even an AR10 subjected to long strings of fire heat transfer can become an issue. I’ve actually moved back away from direct mounting vertical grips and hand stops on my AR15 platforms because at a class or even a heavy round count match that handguard can get real warm…real fast. I’ve since gone back to mounting a rail on my AR15s and attaching accessories to the rail to further insulate my hand from the handguard. Yes, you can wear gloves, but in LE I may not have time to put all my gear on before being thrust into something unpleasant. I try to set up the work rifle so it’s ready to go if I grab it with no time to do anything but yank it out and get to work.
They’re both excellent mounting systems. My personal preference right now is MLOK because of how easy it is to come by accessories in the local gun shop. Magpul also ships all their hardware with thread locker already on the threads. I’ve NEVER had an MLOK component come loose yet. I have had a Keymod accessory or two loosen up on me. However, I’ll take the blame for Keymod since I can’t remember if I had the sense to apply some thread locker before I tightened everything down and took it out. There does seem to be a little more slop in the Keymod system than the MLOK but the MLOK stuff can be a little tricky to set up the first time. The nice thing about setting up MLOK is once it’s set up, it’s just a quarter turn or so to tighten or loosen the system so you can install or remove accessories. If you’ve got your own experiences with MLOK or Keymod, drop them in the comments below!