Midwest Industries M-Lok rail for MR556/HK416

The Midwest Industries entry for the MR556 platform stopped by the lab earlier last week on its way to Z and I thought I would take a detailed look at the M-Lok slick rail. Boasting 7-sides of M-Lok with standard Picatinny up top, 6061T6 construction and an affordable pricepoint ($210 USD), it brings to the table lightweight versatility that doesn’t kill the bank.


First impressions upon unboxing the rail is that it’s coated in lubricating oil – odd, but easily addressed by some mineral spirits. Immediately the lack of weight on the rail is apparent – M-lok channels remove more material than its competitor – Keymod. Midwest has taken this step further by adding subtle scallops on each octagonal edge. Aesthetically this looks odd to me, but this does cut down on the sharpness of each edge significantly especially when using a more traditional grip-style.

The rail comes in a 9″ which is somewhat short for a standard HK416 CQB and exposes the gas block, but works well for a C-length barrel.


Subtle, laser-etched trademarks. Very typical of Midwest who has always stayed along with trends but never invested much in the way of marketing or a good logo design.


Replicating HK’s own design, the captive pin is also present on the Midwest rail.


Borrowing design cues from Geissele’s offering, the profile of the rail is more oval-shaped than round and  requires users to cut the sling loops off of the front gas block.

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A short section of M-lok to Picatinny adapter is also included.


Installation is straight-forward, no barrel nut is provided as it uses the factory nut. The rail simply sleeves over and the cross-bolt is tightened, very drama-less. There is however a dimension-difference between the rail’s anti-rotation lug and the receiver’s key on the VFC HK416 upper.



Once Z mounts it up to his HK416c build, I’ll update this post with link to installed photos.

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