PRI Gen III Delta Carbon Fiber Rail


Precision Reflex Inc has a new rail, and at a glance you can see it’s something different. PRI rails are probably best known in military circles as the rail on the MK12 Mod 0 Special Purpose Rifle (SPR). Moving away from the traditional circular or oval handguards, PRI has gone with their “Delta” configuration.

Click the picture for additional information and images.


  • The triangular form should permit access to any piston system, whether drop in or OEM.
  • The 12.5″ variant shown weighs in at 15 ounces, including the barrel nut, and is certainly lighter than many of the other rail systems on the market.
  • The PRI Delta rail is available in three different lengths for rifle, midlength and carbine gas systems.
  • Black and Flat Dark Earth are available in color options.

This rail was loaned to me by a PRI dealer who has helped me out on a few other projects. Because of this, we were not able to install this rail, handle it very much, or really do much of anything other than grab a few quick pictures. To be fair to the dealer, the rail was left in new condition, and the only the rail itself was handled. The accessory pieces and auxiliary components were left sealed in their packaging. If the opportunity comes up to get one, you can rest assured we will beat on it and treat it the way it needs to be treated, but thats not an option at this point. While I think carbon fiber has solid uses in weight reduction, including on weapon systems, I am unable to make a recommendation one way or another with this rail at this time based on lack of firsthand experience. If you have used the Delta version, please feel free to add comments at the bottom of the thread.

Check the PRI website for additional information and images.


About Author

8 year USAF & Desert Storm Veteran, Current city Police Officer, Armorer, firearm and tactics instructor. Photographer specializing in weapon photography and weapon T&E.

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  1. Ugh my MK12 Mod 0’s rail just became obsolete…it will be tempting to upgrade. Any idea of the A.R.M.S. Swan top rail will still work with it?

  2. Striker2 on

    The ARMS rails do not appear to be compatible with the new Delta handguards. The following s from the PRI website. Describing the new delta handguards:

    The receiver and the rail on forearm are not at the same elevation.

    Describing the older Gen III handguards:

    The long top rail matches the height of the top rail on the standard flattop receiver and is compatible with the ARMS family of rails.

    Also, the profile at the barrel nut is visibly different on the two systems. As the bottom of the ARMS rail is contoured to fit the older Gen III profile, it does not appear that the rail will fit on the new Delta handguard.

    It will be interesting to see if ARMS (or anyone else) steps up to make a similar rail for the Delta handguards.

  3. Interesting, I’m with the other poster that wonders if ARMs will make these rails for the deltas. Older gen models just quite don’t cut it anymore but these rails look promising.

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