The Naked Cartridge

Ladies and gentlemen: Jimmy Wu. He’s a 1st Lieutenant in the Alabama National Guard, an MIT grad in mechanical engineering, and a missile defense systems engineer at Boeing. (Nice resume, hunh?) Jimmy also, in his words, “loves to shoot.” So ammo is the subject in the first of what I hope will be a long line of posts for Defense Tech.

Soldiers hate lugging gear around, especially in a hot and sweaty place like Iraq. But going without ammo — they hate that even more. So they load up on bullets, when they go on patrol.

cased_caseless.JPGA different kind of ammunition, being tested out by the Army, could help. Caseless ammunition give us a lighter round, allowing the soldier to carry more of ’em. A regular cartridge has the bullet, the casing, and the propellant powder inside the casing. In most rifle ammunition, the casing is bigger than the bullet. Caseless ammunition discards the brass and instead molds the propellant around the bullet, giving a lighter and more compact round. For example, a soldier carrying the HK G-11 rifle can carry up to 10 times more ammunition, for the equal weight, than a soldier with an M-16.

Caseless ammunition is not a new idea. The concept has been with us as long as the auto-loading rifle, but it took awhile for the technology to mature. Back in the 1980s, the US Army tried out caseless ammunition under the Advanced Combat Rifle program, but it didn’t go anywhere following the end of the Cold War. Germany did the same to their HK G-11.

Today, following experience in Iraq and Afghanistan, the US Army is paying attention again to soldier load. The Armament Research, Development and Engineering Center has been working on a technology demonstration program, with a light machinegun prototype to be built FY06. Perhaps this time around, caseless ammunition will finally take hold in the United States.

— Jimmy Wu

  • DS

    I imagine a main concern in the development of this would be the amount of residue left in the barrel and reciever. I think a better idea would be to make the bullet out of a harder metal than lead, and make a hollow core inside the bullet, which you can fill with an explosive that is electrically ignited.

  • Emastro

    If I remember right I believe there was a problem with overheating. Cartridge cases make great heat sinks. Add in the factor that ejecting the cartridge acts as a venilation system- removing that can make for a pretty hot chamber-

  • Moose

    Explosive bullets are banned by treaty. With a few exceptions, variants of “ball” and FMJ rounds are it.

  • David

    Yea — I remember heat buildup as a problem in the late 80s early 90s.

  • Byron Skinner

    Good Morning Folks,
    Least anyone forget the M-1A1 and later Abrams Tanks use a caseless 120mm round. The Abrams was not the first U.S. Tank to use caseless rounds the M-551 Sheridan of the Vietnam era uses a caseless 152mm round.
    The use of caseless ammo has been around for years from cannon of the 17th. Century to the 16inch guns of the last Battleships.
    ALLONS,
    Byron Skinner

  • James

    Moose: the bullet wouldn’t be explosive after it left the barrel. And DS’ idea has been used, in fact. The Japanese had an aircraft cannon that fired a shell in 37mm with the propellant in a chamber behind the shell, exhausting gas through holes in the bottom. It wasn’t really a rocket because the charge burned out before the shell left the barrel. It used the pressure buildup inside the barrel to accelerate the shell in the manner of a gun.
    It was, however, a low-velocity weapon, almost more of a grenade launcher than a cannon. The empty powder space was dead weight and drag after the shell left the barrel. Just another idea ahead of its time, maybe, that someone might take up again someday.

  • Tod Glenn

    There’s not only the issue of heat – cases do make good heat sinks and also protect the propellant from the hot chamber. There’s also the problem of obturation. The case swells under pressure and seals the breech. Caseless rounds require an external obturator, and deleoping one that can handle automatic or even rapid fire, and that has a reasonable longevity and is scaled to small arms has proved somewhat problematic.
    The HK G11 seemed to have overcome most of the basic problems associated with self consuming cartridges but its final development coincided with Germanies reunification and the project was a victim of costcutting.
    Perhaps it is time to revisit caseless ammo – aside from weight savings, there should be huge cost savings as wel.

  • Steven

    The one other problem of caseless ammo is that the brass of ammo used now carry away heat from firing. The caseless ammo has no way of getting excess heat away from weapon. Which is way it was never used in war

  • James

    Came across this site, could this be the solution to caseless ammunition?
    caselessammunition.com

  • aoc gold
  • GM

    Say hello to one of the Colt development team!
    DS, you would have serious problems with a thing called Ballistic Coefficient [BC], the reason they use lead in bullets is it is heavy, putting a large hollow mass in your bullet costs weight. and lots of it. you lose effectiveness at range. You would still have just as much residue, so im not sure why you came to the conclusion… no offense of course. An alternative came with the Benelli CB M2, Fiocchi Munizioni developed a round, 9mm AUPO, which essentially used the case as a pusher/obturator/heat-sink/sabot, and has the bullet separately. Call it “semi-caseless” if you will.
    Emastro, that killed most early caseless weapons systems.
    Moose, yes, St Petersburg declaration, 1868. The USA is not party to that, but no arms designers touch it with a ten foot pole, since most countries wont risk having the theoretical enemy start ignoring treaties because of it.
    Byron Skinner, all ammunition was caseless originally; the case was developed as a result of poor breech-sealing qualities in early breechloading weapons. It did quite well but does have an expiry date. When? Whenever technology or neccessity forces it. We aren’t there yet, but it may be soon. It has worked for years in large weapons that cost a lot anyway; they can afford to do it a little “better”. With small arms it is all about mass production qualities. Note that a large cannon has a much larger burn volume/surface area ratio because of its larger bore. This reduces all problems inherent in caseless ammunition design, and also note that it is unlikely to be fired more than ten or so times in a day, and never at a rate of more than a couple a minute.
    James; as you said, it destroyed the BC, and the idea died. Yet again, see AUPO.
    Tod, right on, but dont hold your breath.
    Steven, i think everyone beat you to the point, but you’re right. The largest problems have been as such;
    Breech sealing; machining caught up and this was solved years ago, but is still too expensive to be taken seriously.
    Fouling; solved recently
    Cook-off; never solved, though propellant advances and priming changes have reduced it. Cased ammo cooks off eventually, too.
    Binding; not solved. caseless ammunition really likes falling apart. Even recoil shaking the weapon used to destroy ammunition in the magazine, though we are past that now.
    Waterproofing; Still not solved well. dont get it wet.
    Caseless ammunition is possible, and inevitable, but right now is not viable, even if it is technologically possible. It is far less rugged and reliable than cased ammunition, and combined with the trust in cased ammunition as opposed to the repeated demonstrations of the shortcomings of caseless projects, noone will touch it with a ten foot pole. The CB-M2 was 100% viable and shouldve been adopted by every police force in the western world, but failed miserably because no military ever wants to change and then realize they spent all their budget on something that doesnt work. Once they trust something, it takes a BIG leap forward before they’ll abandon it for something else. Remember; AUPO failed, CAWS failed, G11 failed, TKB-022PM5B failed, SPIW failed. Anything revolutionary is just too “out-there” to be adopted, until it is so sure as to be impossible not to adopt.

  • GM

    expect to see it descend as it gains trust; First large smoothbore guns, tank cannon etc. Then light artillery guns, 50mm, 40mm. Then large aircraft revolver cannon, 30mm, 25mm. Then vehicular autocannon, 20-25mm, then heavy machineguns, 12.5mm, and then small arms. It has to gain trust slowly. Right now we are at the light artillery stage. A long way to go yet before it is mainstream enough for large-scale adoption.

  • Jake

    The one problem with this Idea is that gun heats up very fast, causing bullets to become fragile to the heat (they could go off prematurely, in fast fire rates)

  • Drew

    Almost there in the form of light machine-guns, the LSAT is coming along…

  • Stephen