C4 Rail, 12in Front Sight Pocket Rail Handguard (for Carbine Gas Systems)

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The Centurion patented C4 rail system is a lightweight, rugged, 2 piece free float rail that when installed gives the uppers a continuous 12o'clock rail. 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.
**Please Note: Current version of the rail has some slight cosmetic differences from stock photos
Engraving is now machine engraved and black anodized....no white markings.


Material: 6061 T6

Finish: : type 3 hard coat anodized

Weight: 14.2oz with screws---1.1oz with standard barrel nut

Length: 12.56in (pocket located for carbine length front sight post)

Width: 2.1in

Height: 2.38in

Inside diameter: 1.37

Rails: 1913 spec rail

Fasteners: grade 8 bolts phosphate finished



***Please Note***
- Screws are included with the purchase of all rail systems. Replacement screws are available to purchase if necessary.


  • 5
    C4 FSP rail

    Posted by Justin Lambert on Feb 15th 2021

    Great rail , a little expensive but Centurion Arms makes great items. If you want solid equipment , from a solid company this is it. Veteran owned and operated means a lot. Will continue to buy from them.

  • 5
    Rock Solid Rail

    Posted by Jeremy Sparks on Aug 10th 2019

    Most Rock Solid Font Sight Post Cutout Rail that I have used and it uses a standard barrel nut. No need for proprietary tools. Outstanding!

  • 5
    Great Quad Rail Option

    Posted by Christian Lee on Aug 10th 2019

    If your tool collection is a Dremel, some hex wrenches, and some oil you have everything you need for installing this rail.

    I use this so I can access an adjustable gas block and have an extended sight radius. It's lightweight enough that you can carry it at a class all day long and sturdy enough that when it gets smashed into a door frame at that class it won't bend.