Medium and heavy machine guns are "crew-served" weapons, requiring two and even three soldiers working together to operate it at maximum efficiency. While it's one guy pulling the trigger, the other two carry and feed the bulky ammunition belts into the weapon.
Having to rapidly re-position the weapon therefore brings challenges. According to an article in Soldiers magazine, after a 2.5-hour firefight in Afghanistan, an American infantry combat team started discussing "how three-man teams manning crew-served weapons struggled to stay together over difficult terrain in fluid battles." It goes without saying that a machine gunner separated from his ammo is not good. It would be better if the gunner were self-contained, but that gun's not gonna feed itself.
Or could it? As a joke, one of the soldiers brought up Jesse Ventura's character in Predator, who runs around with a minigun fed by a box on his back. A simple one-person solution, as envisioned by some Hollywood propmaster.
What Ventura's character had was one long, continuous belt feeding uninterruptedly from the pack into his gun. But without that arrangement, the best a lone machine gunner could manage would be to carry individual 50-round belts to load himself—and stopping to reload every 50 rounds. That leads to lulls in fire, and the more times you reload, the more you increase the chances of the gun jamming. This is a design flaw with potentially life-or-death consequences. And so, following the "Predator" discussion, Staff Sergeant Vincent Winkowski thought about it and figured a back-mounted ammo rig might actually be doable.
So Winkowski grabbed an old ALICE (all-purpose lightweight individual carrying equipment) frame, welded two ammunition cans together—one atop the other after cutting the bottom out of the top can—and strapped the fused cans to the frame. To that he added a MOLLE (modular, lightweight load-carrying equipment) pouch to carry other equipment.
"We wondered why there wasn't some type of [system] that fed our machine guns [like the] mini-gun as portrayed in the movie," Winkowski said. "So, I decided to try it using the feed chute assembly off of [a vehicle-mounted weapons system]. We glued a piece of wood from an ammo crate inside the ammo cans to create the decreased space necessary so the rounds would not fall in on each other.
"My Mark 48 gunners, Spc. Derick Morgan and Spc. Aaron McNew, who also had input to the design and evaluation, took it to the range and tested it, and even with its initial shortcomings, it was much better than the current TTP (tactics, techniques and procedures) we employed. On Feb. 26, 2011, our prototype 'Ironman' pack even saw its first combat use by Spc. McNew when our squad was ambushed by up to 50 fighters in a river valley, and it worked great!"
"I'm not impressed!"
Winkowski sent photos of the prototype to advisers from the Army's Research, Development and Engineering Command. The design was subsequently forwarded to the Natick Soldier Research, Development and Engineering Center we mentioned in this post on military bags.
Recognizing the excellence of the design, Natick gave it what's known as an "Immediate-Action prototyping effort." It had been fast-tracked, and in just 48 days a prototype was ready to go. (One significant change was swapping in polycarbonate for the jury-rigged ammo boxes.)
"We pretty much took their design and just reverse-engineered it and improved upon it," said Laura Winters, who headed up the fabrication effort. "Considering where we started from and what we got to, I think it worked very well. It was a very good collaborative effort...."
Then there's what I call the iPod factor:
As [Natick Operations Analyst Dave] Roy pointed out, technology isn't always about the whiz-bang stuff. "Sometimes," he added, "it's merely a simple application of existing technologies in a different format that provides an elegant way to fill a capability gap."
"...We've gotten some initial feedback from the Soldier and from his gunner on how to make some design changes," said Roy, "and we've incorporated the majority of those design changes. Minor stuff, but it's always the minor stuff that makes any kind of system more efficient and more user-friendly."
All of that happened in 2011, with a projected target of early 2012 to get the Ironman formally approved. Looks like it happened—I was able to locate an Army document, dated June 2012, seeking manufacturers for the device. It's been unsexily re-named the Large Capacity Ammunition Carriage System (apparently Ironman was already taken).