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.
A 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
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.
Posted by: Tod Glenn at April 1, 2006 10:03 AM