C4 M-LOK Rail (12in Carbine FSP)

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Centurion Arms LLC is happy to announce the C4 MLOK® rail.

C4 MLOK 12in FSP (For Carbine Gas FSB's)

The MLOK C4 rail system is based off the patented quad rail version. It is a lightweight, rugged, 2-piece free float rail that when installed gives the uppers a continuous 12o’clock rail and MLOK slots for the 3,6, and 9 o’clock positions. The C4 system is the lightest and most rigid rail that clamps to a standard barrel nut on all AR15, M4, and M16 type weapons systems. This design allows the installation of the rail on an upper assembly without removing the front sight post or permanently attached muzzle devices.
Material: 6061 T6
Finish: type 3 hard coat anodized
Weight: 9.8 oz with screws --- 1.1oz more with standard barrel nut
Length: 12.565in
Height: 2.38
Inside diameter: 1.37
Rails: 1913 spec rail
Fasteners: grade 8 bolts with phosphate finish



  • 5
    Looks sleek

    Posted by Balt R on Feb 9th 2021

    MLOK 12IN CUT OUT RAIL was as straight forward install. Great quality, finish and nice way to keep the front sight post and utilize the standard milspec barrel nut. Finish is close or is the same as my LE6920. Thanks Centurion.

  • 5
    Best Centurion Arms Rail yet!

    Posted by FS on Aug 3rd 2020

    I installed a C4 MLOK FSB rail this weekend on an old Colt 6920 that had been relegated to the back of my safe. The lightweight nature of this rail, impeccable build quality, and flexibility afforded by the MLOK slots and extended FSB rail completely transformed my old carbine. I could not be more pleased. And as always, Centurion Arms customer service was second to none. This is the best Centurion Arms rail yet.