FN Herstal FCU Mk3 Upgrade

    At IDEX 2017, FN Herstal introduced several upgrades to the companies Fire Control Unit Mk3, designed to mount to a picatinny rail, and provide a laser range finder/holographic sight and a UBGL launcher. Although the unit is seen mounted on a SCAR 17 with FN’s picatinny mounted GL-1 UBGL, it can be made to work with any launcher on the Military/LE market or in current issue (as long as there is picatinny rail estate). Some features currently with the older Mk3 include automatically adjusted point of aim, indication of weapon cant, pressure pad activated laser range finding, and a reticle with day and night targeting abilities. The Gen 3 version provides a quick attach portion to the rail, larger holographic window, smaller dimensions, less battery power usage, and improved laser ranging abilities. In addition it offers a training safe laser portion, something many militaries require for training at home. The unit is powered by a single CR123 battery, and can reach out to 1000 meters. Although this is almost triple the distance of most 40x46mm grenades in use, it does offer the user an accurate range finder for other applications, or in a worst case scenario where primary range finders go down.

    From FN Herstal

    Designed to enhance all 40mm LV and MV grenade launchers, the FN Fire Control Unit (FN® FCU) uses advanced electronics to simplify range finding and elevation corrections for the operator, even under severe combat conditions. The unit is an advanced sight design for use with any 40mm grenade launcher – stand-alone and under-barrel – and portable antitank weapon.

    Building upon our 15 year history of producing Fire Control Units, the Mk3 has been improved through changes based on electronic modules of the latest generation that combine better performance with reduced size and feedback from user experience with the earlier models. It includes significant modifications to all its modules: laser range finder, ballistic computer, and electronic sight

    A video from FN describing the earlier Fire Control Unit-

    <p><a href=”https://vimeo.com/63651704″>FN Fire Control Unit</a> from <a href=”https://vimeo.com/user5867283″>Miysis Studio 3D</a> on <a href=”https://vimeo.com”>Vimeo</a>.</p>

    FN’s earlier FCU unit-

    My personal input on this system is that like any digital sighting technology designed for 40x46mm Low Velocity UGBLs, is that it is an awfully expensive gadget to what is pretty much a highly lethal and compact potato gun launcher. I think the ballistic design plateau of the 40x46mm UBGL was reached shortly after Vietnam, and hasn’t really improved since. Other than making the launcher itself more compact and portable (H&K M320), the next design plateau will have to be crossed when explosives and ballistics can be made smaller, lighter, and more effective than what current 40x46mm shells are now. Anybody who has fired an M203 or similar UBGL can probably see what I mean here. Sighting systems might improve accuracy somewhat on first round hits, but at the end of the day most of the time these UBGLs are being fired from an off-hand position, while tired or out of breath, and they are very susceptible to wind, last second changes in position or improper trigger control. With minimal training, some experience and iron sights, a UBGL gunner can be extremely effective within 350 meters without the added weight of yet another serialized item.


    Infantry Marine, based in the Midwest. Specifically interested in small arms history, development, and usage within the MENA region and Central Asia. To that end, I run Silah Report, a website dedicated to analyzing small arms history and news out of MENA and Central Asia.

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