5.56 MLOK Rail (9.5in - 15in)

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Our patented CMR rail system is a lightweight, rugged, one piece, free float hand guard that, when installed, gives the upper a continuous 12 o'clock rail. The CMR system clamps to a proprietary barrel nut that can be installed on 5.56/.223 based AR platform systems. It was designed with the top 1913 rail for mounting the most common accessories, yet does away with the need for 1913 rail at the 3, 6, and 9 o'clock positions. Here, other accessories can be directly mounted to it with a dedicated, simple, light-weight, mount. However, it does allow for 1913 rail to be added, if needed, for some less common accessories. Additionally, we built in anti-rotation QD sling swivels in 4 positions. The main objective was to have a smaller, lighter weight, more ergonomic, hand guard that maintains or enhances functionality for the end user. As professional end users ourselves, we know the importance of keeping things simple and that was our design intent here... a K.I.S.S. (keep it simple, stupid) system.


Material: 6061 T6

Finish: Type III hard coat anodized

9.5in- 8.4oz with barrel nut and hardware
10.5in-9oz with barrel nut and hardware
13in-10.3oz with barrel nut and hardware

15in-11.1oz with barrel nut and hardware

9.5in (9.45")
10.5in (10.6")
13in (13.468")
15in (15.044")


Width: 1.39(body of tube) 1.75 (at QD sling swivels)

Height: 1.910(body of tube)

Inside diameter: 1.230

Rails: 1913 spec rail on top

Integrated QD Attachment sockets - Limited Movement



- Currently our gas block is the only one that Centurion Arms can guarantee to fit under the CMR. This is due to the CMR's extreme low profile.

- Screws, proprietary barrel nut, and wrench are included with the purchase of all rail systems. Replacement screws, barrel nuts, and wrenches are available to purchase if necessary.

*** We recommend gunsmith installation for all of our parts.  We cannot warranty items damaged by improper installation.


  • 5
    mlok rail 13"

    I had purchased the c4 rails for other projects and had no problem feeling confident in purchasing the mlok rail when it became available. It locks up tight and has built-in QD mounts. I have put this on two rifles.

  • 5
    Perfect hand guard

    Ever since I picked up the original CMR rail, I hoped Centurion Arms would come out with a MLOK version. The diameter of these hand guards is perfect IMO. I dig how simple and strong all of their hand guards are, and now they come in MLOK flavor! These are the only hand guards/rails anyone needs.

  • 5
    Slim and Trimmed

    This rail came on the complete upper I bought, it is robust yet slim. You'll have no problem getting your hands around it for a positive purchase. Mounting system looks and feels very strong.

  • 5
    5.56 MLOK Rail 15in

    This is a great lightweight rail, it's slim and with the tangs it locks up solid to the upper receiver allowing for perfect alignment. Can't go wrong on the multiple QD connections either! I actually mistakenly bought the M-Lok version but was so impressed with it that I had to build a new upper specifically for it. Lastly the barrel nut design is simple and easy to work with.... no timing to worry about, it just flat out works.

  • 5
    MLOK 13" Rail

    Lightweight, slim in the hand, and most importantly , sturdy . I have this Rail on my CM4 and the same Rail on a 16" build. Totally happy with Centurion Arms products .

  • 5
    MLOK Rail

    Excellent handguard! Light weight, great build quality and beautiful aesthetics to go along with it!