New Artillery Rounds to Help Army Reach Longer Distances

Army researchers test the Extended Range Cannon Artillery platform.

Army photo

LAS VEGAS, Nevada — A new family of 155mm ammunition is being developed to help the Army achieve its goal of improving the reach of its long-range precision fires.

Even before Russia’s invasion of Ukraine — and the resulting spotlight on the likely need for ammunition logistics replenishment — the Army had tapped long-range precision fires as one of its top modernization priorities.

The Army’s next generation 155mm artillery ammunition is one part of the campaign to increase the range of its howitzers and its new 58-caliber Extended Range Cannon Artillery platform.

The new cannon is one of 24 new technologies Army Chief of Staff Gen. James McConville has publicly vowed to field by the end of 2023.

The new family of 155mm ammunition is being developed to increase the maximum range of the current howitzer fleet using 39 caliber length tubes. The 39-caliber fleet will replace the current 14-mile range M795 high-explosive projectile with the 18.5-mile XM1128 base-bleed projectile and replace the current 18.5-mile M549A1 rocket-assisted projectile with the 25-mile XM1113 rocket-assisted projectile.

Base-bleed artillery shells expel gas in flight behind the shell to reduce drag and give them longer range.

The 58-caliber Extended Range Cannon Artillery will be utilizing the XM1210 rocket-assisted, high-explosive projectile — formerly designated XM1113ER — to hit targets out to nearly 45 miles.

As noted in the ammunition descriptions, much of the range enhancement relies on the use of either “base-bleed” or “rocket-assisted” designs.

Kyle McFarland, chief technology officer at General Dynamics Ordnance and Tactical Systems, said he expects to provide the shell bodies for the XM1128 and is the systems contractor for the XM1113 “all up” projectile.

The base-bleed design features a relatively small amount of propellant on the back end of the projectile. That propellant is ignited by the gun gases and the burning propellant reduces drag on the projectile to provide a modest range extension. The relatively small amount of propellant used in base-bleed designs requires only minor tradeoffs with the explosive payload.

“By contrast, with the rocket-assisted projectile, the back half of the round is going to be filled with a solid rocket motor with a nozzle at the end to direct its thrust,” he said.

“That nozzle has some elements in it that are also ignited by the gun gases, which then ignite the rocket motor. The rocket motor gives you a limited amount of thrust during the initial part of the projectile flight, But, as you get more range extension, you have a greater trade-off with your high explosive,” he added.

The new base-bleed and rocket-assisted projectiles will be assembled at the Iowa Army Ammunition Plant, where metal components from places like the General Dynamics operations in Scranton, Pennsylvania, are combined with propellant from Nammo Defense Systems in Mesa, Arizona.

Moving any program from development to production provides its share of challenges. In this new family of artillery projectiles, one of the challenges involves providing adequate amounts of propellant for the base-bleed and rocket-assisted projectiles to meet anticipated production quantities.

Andy Davis, chief technology officer at Nammo Defense Systems, said the XM1128 base-bleed round has approximately 3 pounds of propellant mass at the back end, while the XM1210 rocket assisted round has approximately 12 pounds of propellant.

Davis likened the propellant production process to “making a cake.”

They take liquid polymer, an oxidizer, which is the ammonia perchlorate, and a fuel like aluminum powder and put it in a mixer, he said in an interview on the sidelines of the Shooting, Hunting, Outdoor Trade Show in Las Vegas, Nevada.

“It’s essentially very similar to a KitchenAid mixer you might have in your house, except we have two blades that spin,” he said.

Just like baking a cake, they pour in the liquids, and add the solids in a little bit at a time because if they are put in all at once they are left with something resembling wet sand, he said. They mix it for about 20 hours.

He continued: “What you get at the end of that mixing is uncured propellant, which basically looks like uncooked cake batter. We then pour that into the molds that will make these rocket grains and put them into an oven for a certain amount of time — three days or so — and out pops cured rocket grains.”

Unlike throwing a log on a fire where all surfaces would burn, a second molding step is used to inject an inhibitor, basically a rubber coating with no oxidizer, that helps limit burning only to specific surfaces needed for performance, he added.

“We will eventually ship the propellant to General Dynamics for integration into the rocket motor hardware that gets threaded on the back of the shell,” he said.

Both the rocket-assisted and the base-bleed projectile rounds are made the same way, in the same mixer, he added.

“The modes are different because the base-bleed grains are little squat doughnut-shaped grains, while the range extension grains are about 12 inches long. So, there is a slightly different formulation for the propellant, but the processing is identical.”

Early discussions with the Army had pointed to the possibility of a requirement for 1 million rounds of XM1128s over 10 years — at a rate of 100,000 rounds a year — along with 100,000 rounds of XM1113s.

There is the potential for foreign military sales that could double those quantities, Davis said.

But here’s where the numbers started to get challenging, Davis noted. Until now, all that propellant was produced in a single 50-gallon mixer capable of producing a total of only 500 to 550 pounds of propellant per batch.

“It was going to be impossible to support those [projected] acquisition quantities with that mixer,” he said.

In recognition of that reality, the company invested in the development of a new facility that includes a 300-gallon mixer capable of producing nearly 3,500 pounds of propellant per batch.

“What we did is to build a facility where I can meet the Army’s demand out of a single mixer,” Davis said. “If demand increases, I can essentially knock down one wall, double the size of the building and put in a second mixer,” he said.

Nammo could even go to a larger 420-gallon mixer, or run two mixers under the same roof, he said.

“Not only are we also building a mix building, but you also have to have the facilities to grind the oxidizer into a smaller particle size to help control the burn rate,” he said.

“I need a facility to do that grind work. I need a facility to cast the uncured propellant. I need an oven building to cure the propellant. So, in this project, we’re building nine buildings that will basically run as a factory in a factory,” he said.

The new facility was officially opened on May 25.

Col. Anthony Gibbs, project manager for combat armament systems in the Joint Program Executive Office for Armaments and Ammunition, at the opening said it was “a really important day for the Army,” noting the service’s renewed emphasis on long-range precision fires.

The new Extended Range Cannon Artillery will effectively double the range of the service’s current capabilities, he said.

“Now, that’s a big deal,” he asserted. “And what we have in development right now, two of the projectiles … the XM1113 and the XM1128 … these things work with the propulsion system that Nammo provides, working in concert with the cannon to help us to extend that range,” he said

The Army will be increasing the range of its current fleet of howitzers by about a third, he said.

“So, a 33 percent improvement just with these new projectiles that are going into the field,” he said.

The Extended Range Cannon Artillery platform, which is still in development, has shot about 45 miles, more than doubling the range of its predecessors.

“That is a really big deal as we put that capability out there into the field,” Gibbs said.

“Critical to this effort to deliver this new capability by next year is not just the development, but it’s also the production. And that’s what this facility really represents,” Gibbs said, referring to McConville’s deadline for fielding the system.

The Army hasn’t produced a rocket assisted projectile since the late 1980s, he added.

The M549A1 has served the Army well. It has been a very reliable high performing projectile. But it’s nearing the end of the expected service life, he said.

“Completion of this facility couldn’t come at a better time, not only to meet our modernization priorities, but also because what we see going on in Ukraine right now,” Gibbs said.

Russia’s invasion of Ukraine once again highlighted not only that it’s important to have a trained and ready force, but also to have domestic production capability so industry can scale up when needed, he said.

“We are now once again being called on to serve as the Arsenal of Democracy. And so far, we have answered that call and moving forward, this facility is going to help us do that,” Gibbs said.

Topics: Army News