Colt XM148 Grenade Launcher

Photos by Alan W. I have not seen this style grenade launcher before. It is the Colt XM148. It was the original 40mm grenade launcher for the Colt XM16. However due to the trigger design and the complexity of small parts, easily lost in the field, the XM148 was only fielded for a year in Vietnam. It was soon replaced with the M203.



You can see the extended trigger next to the mag well below.


Nicholas C

Co-Founder of KRISSTALK forums, an owner’s support group and all things KRISS Vector related. Nick found his passion through competitive shooting while living in NY. He participates in USPSA and 3Gun. He loves all things that shoots and flashlights. Really really bright flashlights.

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  • Cybrludite

    I’m thinking that trigger is a recipe for an ND, which would not make you popular with what’s left of your squad.

    • Nicholas C

      Yep. According to Wikipedia it was one of the reasons that it was no well received.

  • PBAR

    The USAF held on to theirs at least up until the early ’80s.

  • Harry’s Holsters

    Looks like the granddad to the HK launcher.

  • Charlie Taylor

    looks like there’s a grip safety on there, which would help with the exposed trigger. But then you’ve got to deal with the fact that you can’t fire the grenade launcher without moving both your hands. If you just held onto the grip safety all the time then it would defeat the purpose. So many problems with this design.

    • I think what you are referring to the grip safety is the latch to pop open the breach.

      • Charlie Taylor

        ah, do’h

  • TheNotoriousIUD

    Sweet rifle.

  • Iggy

    Other merits or lack thereof aside, looking at this makes me realise an overlooked advantage for bullpups:

    • In addition to a more ergonomic/inline trigger for the GL, the other huge benefit of the bullpup/GL combo is weight distribution.

      Because the Bullpup puts much of the weight of the firearms action to the rear, it helps offset/counterbalance the 2-3lb weight in the front of the grenade launcher.

      This is important, as reducing total frontal weight reduces the mechanical leverage against the wrist and support arm.

      • iksnilol

        I thought the weight distribution was the primary advantage, the trigger thingamajig is just an added on bonus.

  • Here is the patent for Colt XM148.

  • SerArthurDayne

    This was actually extremely popular with Naval Special Warfare throughout Vietnam-

    You should read the book series from Master Chief Gary Roger Smith, USN SEAL & Master EOD. He describes many times how much more effective he felt the XM-148 was , IN PARTICULAR due to the trigger, which after adjustment to the user allowed an operator to keep their firing hands on the pistol grip of the M16/CAR-15 and extend their trigger finger forward to the XM-148 trigger. …. Whereas with the M-203, it required completely removing hands and grips and changing grip/aim posture. He felt not only was he more accurate with this, it was much safer for him because it allowed him much quicker recovery & follow-up rifle shots in an emergency or of course during a firefight.

    I’m not saying, I’m just saying. Obviously I have no experience with the XM-148.. I have read this gentleman’s 3 books (the first two are Vietnam centered, the third is half Vietnam and half his post-war career in myriad training courses, diving, EOD, US Army Sergeants Major Academy, etc.) — they are really great to read if you’re interested in the Vietnam War or Special Operations Forces.

    • iksnilol

      Can’t you fire the M203 with your left hand? You don’t even shitft the grip much if you support the magwell with your support henne.

      • SerArthurDayne

        “i don’t operate bro” but here is a passage from Master Chief Smith’s 2nd book, “Death in the Delta” … he’s talking about a time he borrowed an M16 and M203 from another SEAL Platoon on Sea Float, because he just got assigned there as an adviser to the Biet Hai and needed to borrow some gear & weapons.

        “….followed by familiarization firing twenty 40-mm HE rounds from the M-203. I sure wished it had a trigger that could be adjusted a bit forward and outboard of the M-16’s trigger, similar to that of the XM-148. I didn’t like having to move my right hand away from the M-16’s pistol grip forward to the M-203’s trigger. With the XM-148 I could continue grasping the pistol grip, move my trigger finger one inch forward, then fire the XM-148. It was simpler, faster, and I was more accurate with it. But the M-203 setup would have to do for the time being.”

        I don’t know stuff about stuff, I am just saying- there was a ton of support from Naval Special Warfare for the XM-148. Not just this gentleman. I have read a ton of books on SEALs (and US Army Special Forces, USMC Force Recon, MACV-SOG, LRRP/Rangers, etc.) in Vietnam and the Vietnam War and many were big on the XM-148 (it was a big time SEAL preferred weapon, similar to the “Cut M60” and even the Stoner LMG.)

  • jono102

    In Vietnam, Both the NZ and Australian SAS had them mounted on a few weapons, incl some L1A1’s with 30rd mags, auto sears etc. Seen images of them even on a L34A1 Sterling SMG

  • mechamaster

    How much the weight of the launcher itself ?
    The M203 unloaded is ± 1,5 Kg

  • SerArthurDayne

    I didn’t know that, but I did know — and is well documented by Master Chief Smith in “Master Chief” and other Vietnam-era SEAL books I have read, that the USN SpecWar and Australian SAS have a long and established history and collaboration and love each other.

  • jerry young

    In Viet Nam in the 70’s we had what I believe was called the M209, it was an M16 with a grenade launcher mounted like this but this wasn’t it, it was a version of the M79 grenade launcher if I’m not mistaken, as I recall it was a lot less complicated than this