Army invents new heavy barrel for M4


I saw this going around the various facebook gun groups last night. It’s funny that its “invented” Like spiral barrel fluting hasn’t been around since dirt was a new thing. In fact, I would even bet Colt played around with this idea at some point 20 years ago and the Army said no.

Two small arms engineers at the U.S. Army’s CCDC Armaments Center have invented a new M4A1 barrel for extended cyclical fires.

On Tuesday, the Army was granted a 15-year design patent, which is now available for license to businesses that would manufacture the barrel.

Thomas Grego and Adam Foltz designed the heavy barrel at the Picatinny Arsenal in New Jersey. It features spiral fluting in three distinct areas that increase the exterior surface area of the barrel as well as reduce overall weight.

The new barrel dramatically reduces the risk of barrel failure or premature ammunition detonation, i.e., a cook-off, by diffusing heat faster than the conventional M4A1 heavy barrel, which soldiers had reported were failing during combat in Afghanistan.

“(The M4A1) allows us to fire a better suppressing fire,” Lt. Col. Terry Russell told the Army Times in 2015. “At some point, a barrel is going to bend. It could be solid steel, but as soon as you reach a certain heat point it’s going to do some damage to the barrel. … But (the improved barrel) would have helped out to a certain degree.”

The new barrel’s fluting has fin spacing and a thickness that is optimized for heat dissipation and weight; the fin height gradually tapers down.

The design patent is the second patent the Army has received for the new barrel. In April, a 20-year utility patent was also granted.

Brian Metzger, a senior technology manager at TechLink, is facilitating licensing discussions for companies interested in producing the barrel.

“The design patent reinforces the utility patent, makes it a complete package for a licensee,” Metzger said Wednesday morning.


  1. Agreed, spiral (and straight, dimpled, et cetera) fluted barrels have been around for a long while.

    In this case, it sounds like the specific details (e.g. variable flute spacing (thread pitch?), variable profile of the flange or vane between the flutes, and specific details of both), is what’s new enough to grant the patent. If so, fair enough; patents are often granted for taking an existing concept and making it somehow better. Otherwise, it’d be impossible to patent, say, a better formula for tire rubber, or smokeless powder, once the very first one was developed. (Not to brag, I have one or two like that myself so – in my field, anyway – a little insight on how much “different” is enough.)

    I wonder if the barrel was designed for a particular handguard.

    • Nobody likes a systems thinker 🙂 Just ooh ahh at the shiny please, peasant!

      Having said that I’d also like to see their cook off testing results.

          • That wouldn’t be surprising. An organization that considers itself as a research organization (or likes to think of itself as such, even if it isn’t), often counts patents, journal articles, conference papers, etc., as indications of productivity or “return on investment” for research.

            Certainly it looks good on the resume of the inventor, especially if working in a field that for whatever reason can’t generate a lot of published research.

          • of course it won’t. the extra time and expensive of making those sprial fluting cant be justified. not that the army has any problem wasting billions Colt, Fn etc would lose money if they didnt jack the price up big time for making barrels like that. and of course the amount of ones that wouldnt pass spec after being made would be huge compared to normal SOCOM TDP barrels.

  2. Knowing the Army’s history on stuff like this, I’ll lay you long odds that they stole the design from someone who was “outside the system” and who submitted it. Then, these assclowns filed off enough of the design elements, and then “patented” the remnant as their own work.

    They’ve done it before, twice to MagPul, and innumerable times before.

    Rule of thumb? Don’t be Crye, and trust the Army. Most of the procurement people are crooks, and they’ll do everything they can to rob you blind of your IP.

      • I’ve heard the rueful comment that the best way to get your stuff patented for free is to show it to the nice people at Natick, and then they’ll do it for you.

        With their names on it.

        Happens a lot in the nylon gear industry. I knew the guy who founded Tactical Tailor up in Tacoma, and the litany of crap they outright stole from him and others in the industry is nauseating. The bastards at the Ranger Regiment took the MAV, which he’d worked up on his own dime with some input from guys at 2/75, and then turned it into the RACK, having it built out East by guys like London Bridge Trading, and never once either compensated or acknowledged his work. Logan Coffey was a great guy, an innovative designer, and entirely disrespected by a lot of people in the procurement pipeline. Even when the guys he knew who respected him and his work came out to Tacoma to have him give input, he’d have to watch out for the remoras they brought in tow who would try to rip off his work. There were a couple of incidents where he had to go over people’s heads in order to stop BS from happening with things that the Natick assholes had seen out at his plant. Logan’s death was a serious loss to the equipment industry and soldiers everywhere. I’d suspect there was something fishy about it all, as well, but we all know that things like that just don’t happen…

  3. And they still left the stupid M203 notch in it. Even though the M320 is supposedly replacing the 203 force-wide, and doesn’t require the notch to mount up.

    • That did seem strange. Maybe it is part of how they justified the new patent (“interrupted fluting”, etc).

      • I like that.
        Or maybe they justified it by saying “see? Still an M4 barrel, you can tell by the notch! And that makes it back-compatible with the legacy 203s we still have on hand!”

        Because I’d wonder if interrupting the spiral for the gas journal would get credit for interrupted design, and then a “progressive spiral rate” fluting beyond wouldn’t be worth its own patent(s?).

      • I also just noticed that the flats under the handguard for the original SOCOM profile are gone, or seem to be. Which means the 203 notch is superfluous, because the rear mounting flats are gone anyway, so you possibly can’t mount the 203 even though the notch is there.
        As I understand it anyway. I’ve never actually mounted or fired a 203 from a military M4A1, heck I’ve never even been in the service at all, any branch for any duration.
        But this seems like a theoretical step forward in some ways, and institutional-inertia-stupidity in others.

  4. Why not just invent and patent a miniature phase-transition cooling device and a barrel with coolant passages in the first 12 inches for flowing the coolant around the barrel?

    I’m being sarcastic, of course. We might as well re-invent the water cooling jacket from a Browning 1917 machine gun.

    What an absurd waste of taxpayer money.

    • Somebody is going to do it. Whether or not it’s worthwhile…?

      I’ve often wondered why the hell they aren’t doing more research with TEG, to try and leverage the technology for barrel-cooling. The tech ain’t there yet, but if we don’t do the research, it never will be. Being able to make use of that massive heat differential sure seems like a no-brainer, but that’s just me…

      One other aspect of all this that doesn’t get a hell of a lot of consideration at this point is thermal camouflage–At some point, thermal imaging is going to be so ubiquitous that we’re going to have to be able to reduce signatures, in order for such things as machineguns to even function on the battlefield. So, where the hell is the research? Best be starting now, boys, or you’re gonna wake up in a world dominated by Predator-like sensor systems, and be cut down the moment you unmask by firing your weapon and getting the barrel all nice and noticeable by heat signature…

      • forget about all the crazy talk. the real threat in the immediate future will be Putin’s army storming miami beach wearing level 8 hard plate armor so we got to have a super 6.8 round to stop them!

        • Level 8, eh? Well, I suppose the solution to that is to back off and wait for them to expire from heatstroke in the Miami humidity…

          You want fun? There are two ways to get it: One, you take a kid who grew up in Miami and who went through Basic/AIT at Fort Leonard Wood in the summertime, and then drop him for his first tour in Korea, then take him out into the field for Team Spirit preparation around December… Much LOL to be had, trying to keep that poor bastard alive under those conditions.

          The other one? Take a kid from St. Petersburg, who has never ever lived in a really hot climate, and then dump his ass into Fort Polk, LA in the middle of summer. Oi, the fun keeping that young man away from the horrors of heat injury. I had to dump out our cooler into an improvised ice bath made from a truck tarpaulin and a dug-out hole, and then send for all the ice in their unit mess section. We were floating blocks in there with him, and the medics still couldn’t get his temps down. Later reports had him medically retired for permanent heat injury, and the whole thing just snuck up on everyone in the chain of command, including the medics. Huge-ish mess.

  5. Is there any reason you couldn’t rough something like this up using rotary cold hammer-forging? Save the money by leaving it rough, and then just machine where you need to?

    There was a guy I talked to once, about barrels: His contention was that the best way to build an effective, long-lasting and accurate barrel was to run the hammer forge in the opposite direction to the rifling, such that the twist of the rifling would work against the crystalline structure built up from the hammer-forging twist. In the course of the conversation, he lapsed into such erudite and esoteric diction that I quite lost track of whatever the fuck it was he was trying to communicate, and that snippet is all I retained. His contention was (I think…) that the opposition of twists would enable much greater barrel life and accuracy.


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