M-LOK vs Picatinny

It was not long ago that shooters had one of two choices when it comes to forend accessory systems: the proven, yet slightly heavy and snag prone Picatinny rails. Or a variety of proprietary mounting systems that are lighter, lower-profile and unique to one of a variety of manufacturers, each requiring different accessory mounts. Now that firearms owners find themselves twenty years deep into the 21st century, when it comes to accessory mounting on handguards, the decision tree for forend systems has two main branches: the veteran Picatinny rails and the modern M-LOK slots. So, which one is right for you? Let's take a look at the details surrounding both M-LOK vs Picatinny attachment systems.

Choices - M-LOK vs Picatinny 

Between the military, law enforcement and civilian shooters, there are millions of carbines and rifles in use in the United States. And with a heavy focus on usability and practicality, the AR-15 style rifle has grown into a modular weapons platform that can be used for a variety of applications ranging from competition shooting to home defense. Becoming a platform is an important process; attachments need a solid and universal system that the industry can support with mounting solutions. And on top of all that, it needs to be light enough to avoid front-end weight, which can cause fatigue.

I. M-LOK vs Picatinny - Details and Specifications

MIL-STD-1913 Picatinny Rail

With humble beginnings as an optic or sighting attachment system for rifles, development of a simple yet robust accessory mounting system for forend and handguard accessories started decades ago. Picatinny rail accessory attachment development began in the early 1990's and was finalized in 1995 as the MIL-STD-1913 accessory rail attachment system. The military, law enforcement and civilian shooting world finally had a standardized way to attach optics, sights, lights, lasers, night vision devices, bipods and other accessories made by manufacturers around the world.


  • Picatinny locking slot width: 0.206 in (5.23 mm).
  • Spacing of slot centers: 0.394 in (10.01 mm)
  • Slot depth is 0.118 in (3.00 mm)

Magpul Modular Lock - M-LOK

Launching as part of the MOE system from Magpul around 2007, the M-LOK system uses an industry standard size slot system. In combination with accessory mounting systems that use a rotating internal lever that is loosened or tightened with a hex key, lights, foregrips and a host of other attachments are securely fastened in a slot on a handguard. The M-LOK system can save on unnecessary weight, reduce the outer diameter of the platform itself and has a smoother outer face, reducing the potential for snags on other gear in use by the operator.


  • Slot length: 1.260 in
  • Slot Width: 7mm (0.276 in) wide and
  • Space between slits: 8 mm (0.315 in)
  • Radius of the corners: 2.38 mm (0.094 in) approx

M-LOK Torque Specs:

  • 4.0 N⋅m (35 lb-in) metal accessories to metal handguards.
  • 1.7 N⋅m (15 lb-in) polymer or metal accessories to polymer handguards.
  • 1.7 N⋅m (15 lb-in) polymer accessories to metal handguards.

II. M-LOK vs Picatinny - Attachment Methods

When it comes to mounting equipment to a forend or a handguard, there are several considerations that the end user should take into account:

  • Quick detach capabilities - The need to add or remove a device quickly without the use of tools.
  • Solid mounting and ease of use - The ability to easily add or remove a device, even under duress.
  • Repeatability - Removing and installing an optical or aiming device while maintaining a zero on the same weapon system

III. M-LOK vs Picatinny - Handguard Profiles

Besides the ability to add and remove accessories, two of the biggest considerations when selecting an attachment system is weight and bulk. In general, M-LOK systems weigh less than their Picatinny counterparts because they don’t require the extra mass of external rails.

It may seem obvious at this point, but Picatinny rail systems require larger outer diameters than M-LOK systems. A quad rail (top, bottom and sides) requires space for the external rail as well as clearance for the equipment being attached. In comparison, since the M-LOK system does not utilize an external rail for attachment and does not require clearance for attaching devices, an M-LOK system can have a smaller overall outer diameter.

IV. M-LOK vs Picatinny - Final Thoughts

Much like the decisions that go into buying a firearm or any other piece of gear, there is no right or wrong answers when it comes to picking M-LOK vs Picatinny mounts. In most cases, an experienced shooter will own and use both attachment systems at some point over the course of their lifetime and will be able to judge accurately for themselves the pros and cons of M-LOK vs Picatinny accessory attachment systems.