XM-148: Colt’s Vietnam Grenade Launcher


While the Special Purpose Infantry Weapon (SPIW) program failed to produce any successful rifles, it did become clear that the area-effect aspect of its requirements did have merit. This was spun off as its own program to develop a 40mm under barrel grenade launcher for the M16 rifle. Of the initial entrants, (Philco/Ford, AAI, and Colt), Colt’s CGL-4 was the most promising. It was moved quickly through development and 10,500 were ordered in January 1966 as the XM-148. Field reports quickly turned sour, though, and in May of 1967 the XM-148 was ordered out of combat use, to be replaced with the M79 grenade launcher. The idea was sound, but the execution needed improvement – which would come in the form of the M203 launcher instead.

Many thanks to Movie Armaments Group in Toronto for the opportunity to showcase this grenade launcher for you! Check them out on Instagram to see many of the guns in their extensive collection.


  1. The sling swivel on the front of the rifle hand guard seems like it should have been removed to avoid a rather bad day on the first shot, as it appears to hang down slightly into the path of the projectile.

    • In my experience, the drill was to fold the front swivel up and back when remounting the launcher after cleaning, so as to avoid that problem. Although what happened was that the swivel was banged upward by the ogive of the grenade round as it left the muzzle, leaving a mark on the underside of the rifle barrel but otherwise not causing problems.

      As to how I know this, in the late 1970s the Federal government disposed of a lot of the XM148s by way of LEAA (Law Enforcement Assistance Authority). They were given out to police departments modified to use 37mm tear gas rounds, as a replacements for existing 37mm tear gas projectors such as the Smith & Wesson Model 210, that in some cases dated to the 1930s and were nearly worn out from use.

      The idea was that in a SWAT team, instead of one man being armed with only the 37mm tear gas launcher, he could have an AR-15 with an attached launcher, the XM148.

      XM148s in this mode were still seen in some U.S. police department armories as late as the turn of the 21st Century.

      Today of course you can buy 37mm launchers that are essentially copies of U.S. and other 40mm launchers with proper licensing. Most of the “grenade launchers” seen in movie productions are these 37mm “clones” rather than the “real thing”.



        • Well, the reason you don’t need papers to get a 37mm flare launcher is that flare launchers are impractical to use in anything except the intended use so long as you’re loading flares, smoke/tear-gas, or noise-effect rounds, and absolutely nothing else. Anything considered remotely anti-personnel (like bean-bag rounds or buckshot) requires a destructive-device registration. Let’s don’t even get into why you’d need police-type ammunition unless you are a cop!

  2. So now that YouTube is advertising on your videos again, are you getting a cut of that even though you’ve demonetized the channel?

  3. Understand Air Force security personnel had a few of these, seen in their hands up till the late 1980’s. possibly early 1990’s.

  4. I am surprised that such a ‘Christmas tree’ of a design with so many add on and protruding parts and with so many quite obvious shortcomings (what were an experienced firm like Colt thinking of – having an off day?) got past testing and trials – a function of the overriding push to get something in the field?

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