FN Fire Control Unit (FN FCU)

FN Herstal has developed a 40mm grenade launcher sighting system called the FN Fire Control Unit (FN FCU).

FN FCU mounted on FN SCAR

The FCU is mounted on a picatinny rail above the launcher. A laser range finder calculates the distance to the target and a clinometer measures the angle/elevation to the target. A ballistic computer then calculates the required angle of fire and a red dot sight is moved to point at the correct aiming point. The cant indicator will tell the operator if the weapon is canted and require realignment.

As you can see in the photo, iron sights and/or optics can still be used. This system could be used on standalone launchers or under-barrel launchers.

It looks good in theory, as do other 40mm laser sighting systems, but I have heard from various readers that one system, the H&K M320 laser sighting system, is not very useful in the field and I wonder if the problems with that system also apply to the FN FCU. Back in 2008 Sean wrote …

I was a grenadier in the Army and deployed to Afghanistan in ’06 where they tried to foist that sight on us, and to a man, we hated it. firing a 203 is easy; couple of trips to the range, you’re good to go. it’s just about learning angles and distances and generally being comfortable with the weapon. once you’re there, you can fire, as a guess, 20 or so accurate rounds a minute. that sight cuts that in half. i don’t know much about the 320, but that sight has got to go.

Sean elaborated here.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Brian Lau

    This is the same tech as in the F2000 Grenade Launcher

  • Joel

    That’s a ton of weight out front.

  • Entropy

    What happens when you drop it or bang it into a wall accidentally? I know you’re not supposed to do that to your rifle, but a forward-mounted assembly that sticks out as much as that does is going to take a bit of a beating over its service life. I hope the optics are able to withstand that.

  • Sobral

    Damn! Does it have the iPad attached? I wonder if is the 2th release or the first of the iPad…. too geeky… I wonder if it is combat proof… Doesn´t look too reliable in the mud and rain…

  • jay1975

    I have to agree with Sean here. I was a assigned a 203 for several years and can put a round on target at 300 meters with just the standard leaf sight with no problem. It is an easy to fire, general area weapon. Five meter kill zone allows for plenty of wiggle room.

  • Aurelien

    Got my hands on it a few years ago. Thats a cool gizmo, and it’s not really for the open-ground fire, more for accurate grenade shots trough windows or behind walls. Like the system on the XM25, you can flash a wall, then tell the computer to aim for the other side of the wall.
    The guys at FN told me you can just reprogram the thing when you change launchers, so you can use it with 12″ 203, 8″ 203, M320… Even Russian GP25 or 30.

    But then again, i believe it’s better to train without it. It’s more a “special occasions” kind of thing.

    • Aurelien, it was around a few years ago? FN have been claiming it is new in their recent press releases?

  • Fancy electronics on war scenarios, fragile, fanciful, unpredictable.
    Manufacture a real SOLID STATE logic system, then try these stunts again.

  • TCBA_Joe

    My buddy was in 1/75th. As a grenadier he was issued the all the fancy laser sighting units which weigh a ton, but add little value. He refused to carry it. On mission, his BC was furious when he saw that he wasn’t using his issued gear, up until he dropped a 40mm through a door at 200m with no sighting system.

    Firing these systems are very easy if you have the minimum alotted range time. It’s more akin to throwing a baseball than firing a rifle. However, companies like FN, HK, and Insight need to make money, so if they can convince our military’s purchasing authority that we “need” these systems, they will. If you spend 10 minutes in any unit you’ll find 10s of thousands (if not 100s of 1Ks) of dollars in “stuff” that may have utility on paper, but was not designed with the imput of those on the ground who need (or don’t need) it to fight.

  • gunslinger

    in theory, all the computer systems are great. set the firing distance, auto update sights…the drill. however is it actually combat proven? if you fire once and the thing falls apart what good is it?

  • Jason

    That doesn’t look the least be cumbersome.

  • charles222

    The 320’s sight is easy as hell to use; I’ve used it on an M203 before and it took just about any guesswork out of shooting it.

    And I’m pretty sure that a company like FN is pretty good about break-proofing their shit. These people have had a military focus since before WW2.

  • rich crane

    This is news? Mebbe 4 years ago. If this sight was worth a damn, someone would be using it?

  • el jefe

    you could remove the gun from this scifi tech-pile and noone would even notice

  • Jake

    Seems like it might block the front sight a little.

  • The Other John C

    Yeah it sounds like a good idea, but in the time it takes to do all the measurements and stuff, you could have fired 2-3 shots and one of them would have hit the target.

  • Elkroppo

    This might help plop a round in a fifth story window. The leaf sight works great for level shooting, but it is hard to adjust for changes in elevation when the round is that slow.

  • Aurelien

    Well i recall having it in my hands at Milipol 2 years ago, but maybe it was just a prototype at the time. The preseted it at about the same time as the “round counter” AR pistol grip.

    It seemd like a nice thing at the time, mainly because it’s built around the iron sights of AR-style rifles (not obscuring them), adds a laser rangefinder (the thing actually tells you the distance to target) and works like your average red-dot sight.

    The guys at FN were adamant this is for precision grenade shooting, when you don’t have the luxury tu miss your target on the first shot. On the modern urban battlefield with tight ROEs, it could be pretty handy.
    And like all the electronic stuff, does not get you a pass on training with a “naked” rifle, just in case.