SIG SAUER - Never Settle

MDM 17 – Geissele Automatics Super Modular Rail MK16

The Upper Reciever in this photo is equipped with the M-Lok standard, Super Modular Rail MK16 Rail, from Geissele Automatics (but in Desert Dirt Color rather than Black), and Super Charging Handle as well as a Daniel Defense Barrel and Gas Block and finished off with a SureFire WarComp. US Army Special Operations Command, as well as others, are said to be looking at this configuration. Despite being referred to by some as “URG-I” (Upper Receiver Group Improved) these are parts, intended to replace existing components, giving their M4A1s an update. The Super Modular Mk16 is not available commercially.


For those of you familiar with the Geissele Gas Pedal, that’s one on the lower. It’s ambidextrous and offers a 45 Deg throw from Safe to Semi. The real magic is when you depress the spring-loaded Gas Pedal, offering momentary Full Auto performance, as long as it is depressed. Let go, and the weapon reverts to Semi Auto mode. It takes a couple of magazines to overcome muscle memory associated with the full 90 Deg throws of a standard Selector, but it’s a very fast transition from Semi to Full Auto. There’s no more fumbling with the Selector, just push the Gas Pedal and Rock and Roll. This is an upgrade DoD should consider immediately.



20 Responses to “MDM 17 – Geissele Automatics Super Modular Rail MK16”

  1. 3isen says:

    Leave it Geissele to make the magic happen.

  2. Alex says:

    What sets the MK16 apart from the MK14? They both appear very similar.

    • SVGC says:

      This variant has mlok slots in the 11, 1, 5, and 7 o’clock positions unlike the Mk14, which is just 3, 6, and 9. I’d venture a guess that it has a little bit larger OD as well. Personally I think this is what the mk 14 should’ve been but they still got there anyhow.

  3. JAdam says:

    Is that a 14.5″ barrel with a mid-length gas system?

    The MK16 in the grainy photo looks to be a little rounder than the other MK models, no rail on the underside and MLOK all over the place. QD location has also changed it seems.

  4. mark says:

    I would love to see a civilian version of the High Speed Selector/Gas Pedal for the Echo trigger.

    • ClickBoom says:

      I can’t see Big G designing a selector for another aftermarket manufacturer’s proprietary trigger.

      Not for business reasons, though. They wouldn’t be able to retain QC of the interface, as it would depend on the QC of the Echo trigger. G only makes awesome stuff – this leaves too much out of their hands.

      ….to humor your question. Heh

  5. Alex says:

    Sounds like the Upper that was previously mentioned a few months back.
    The one thing that stands out in my mind is the choice of DD barrel.
    One wonders the profile, gas system, gas port size… or if it’s the same setup as a Colt M4A1, why it was chosen over the Colt or FN

  6. RockyMountain9 says:

    Sounds like an abysmal idea. More a trinket than a fighting solution. Would have expected better from Geissele.

    • RockyMountain9 says:

      (Regarding the “Gas Pedal”)

      • Mike says:

        Sounds like you need to educate yourself as to why they made it.

      • BillC says:

        Throwing the selector to full auto has been shown to be quantifiably slower than switching to semi. This allows the user to momentarily engage to full auto just as fast as it would take to throw the selector to semi now if full auto is needed, and then easily re-engage to full auto from semi, or automatically get back to semi when full auto is no longer demanded.

        It’s not a trinket. It has its purpose, and it’s ingenious.

      • SSD says:

        No, you are completely wrong. The standard throw to Full Auto is not ergonomic. Coming back to Semi, you are as likely to go all the way to Safe as Semi, particularly under stress.

  7. E. O. Shultz says:

    Similar rail to the previously reviewed VSASS, no? With the exception of the recess at the front?

  8. n8 says:

    If you pin the trigger after firing a semi-auto shot and push the selector to full-auto does the gun fire full-auto? There’s nothing magical about that, it’s pretty easy to do with just a selector design. If they fixed that, then it’s a little more impressive, but not hard to do regardless.

  9. NiceRail says:

    This should be made commercially available. The more tubular design is better ergonomics. At least open it to LE groups too, until you can roll out commercially.