SPG with fully automatic firing cycle: SIGMA aims for the US Army
SIGMA / "Roem" from the Israel Defense Forces (IDF) fleet
Several years ago, the Israeli company Elbit Systems first demonstrated a self-propelled artillery A wheeled chassis-mounted self-propelled gun called the SIGMA 155 was developed. This product was subsequently promoted internationally. The US military is currently being considered as a potential customer. An improved version of the self-propelled gun, the SIGMA NG (Next Generation), is planned for them, and American industry is being involved in this project.
New plans
Elbit Systems' American subsidiary unveiled its new plans in early June. The company announced its intention to submit the SIGMA system to the Pentagon's competition. The SPG modernization will be carried out in partnership with the American company Anduril Industries, which has extensive experience working with the US Army and possesses the necessary technologies. A cooperation agreement has already been signed, and the terms have been finalized.
The upgraded SIGMA NG self-propelled gun for the US will generally retain its original appearance and architecture. However, according to the developers, a major upgrade to the onboard electronics suite is planned. This primarily involves integrating the self-propelled gun into the existing command and control systems of the US and NATO ground forces.
One of the project's stated goals is localization of production. The maximum number of parts, components, and assemblies for the SIGMA are planned to be manufactured at American facilities. According to the company's calculations, this should simplify and reduce the cost of production and long-term operation, as well as reduce the risks associated with international cooperation. More than 300 American companies and related suppliers are expected to be involved in the production of the self-propelled guns.
Official reports indicate that Elbit Systems and Anduril Industries have only just agreed to cooperate and concluded the necessary agreements. Actual work on upgrading the self-propelled guns, if it has begun, is in the very early stages. The timeframe for modifying the existing design has not yet been announced.
Why is the US interested?
The Pentagon's interest in a wheeled self-propelled gun of this class stems from the recent failure of its own program. The ERCA (Extended Range Cannon Artillery / XM1299) project, which envisioned the creation of a tracked, ultra-long-range self-propelled gun with a 58-caliber barrel, was canceled due to technical issues, primarily excessive barrel wear and unstable automatic loading under high pressure.
Following the closure of ERCA, the US Army shifted its focus to off-the-shelf, mobile, tactical wheeled solutions. Elbit America fielded the SIGMA in the US, positioning it as a replacement for the M777 light towed howitzer and a complement to the Stryker wheeled brigade. Thus, a niche opened up precisely when the company already had a production vehicle ready.
Self-propelled gun at the market
Development of the first version of the SIGMA 155 self-propelled gun began in 2017. The project was initiated by the Israeli Ministry of Defense, which wanted a modern wheeled self-propelled gun that would surpass existing ATMOS products in key performance characteristics. Elbit Systems was appointed as the lead developer.
Experimental self-propelled gun for the Bundeswehr
Within a few years, Elbit completed the design and built a prototype of the new type of equipment. In the early 1920s, the first firings took place at the firing range. Following the testing, a contract for serial production and supply was signed.
In 2023, the first batch of serial SIGMAs arrived in the IDF's 282nd Artillery Regiment. The self-propelled guns were accepted into service under the name "Ro'em" (Thunderbolt). In 2024, the first firing tests took place at a firing range, simulating actual combat operations. As early as April 2026, shortly before the events described, the self-propelled guns were used for the first time in combat: they fired at targets in southern Lebanon.
In November 2021, Elbit Systems announced its first export contract. An undisclosed number of SIGMA self-propelled howitzers were ordered by a Southeast Asian country. The details of the order remain unclear; it's not even known which country placed it.
In late 2022, the development of a new version of the SIGMA was announced. It was developed with the participation of the German concern Rheinmetall Defence for participation in a Bundeswehr competition. This modification was generally identical to the base model, but differed in its chassis and included some minor innovations. The first demonstration firings took place in March 2023.
However, major European orders were unsuccessful. The RCH 155, developed by another German company, KNDS, won the competition for key procurement contracts between Germany and the UK (under the Mobile Fires Platform program). The UK and Germany agreed to a joint purchase of up to 400 units of this vehicle. Neither the Swedish Archer nor SIGMA were able to compete in this tender: the Bundeswehr opted for commonality with its existing fleet of Boxer armored vehicles, on which the RCH 155 is based.
Competitive environment
In the heavy wheeled artillery market, SIGMA competes with two serial, proven European projects, each of which has its own conceptual advantage.
Archer (BAE Systems, Sweden) is built on a 6x6 or 8x8 chassis. Its strength is its rapid response: the first shot is claimed to fire within 20 seconds of stopping. Its weakness, compared to the SIGMA, is the smaller ammunition capacity in the autoloader: 21 rounds, after which it must be reloaded from the transporter/loader vehicle.
RCH155 (KNDS, Germany) is built on the Boxer 8×8 armored personnel carrier chassis. Its key feature is the ability to fire on the move, without deploying outriggers; the crew has been reduced to two (compared to three for the SIGMA). The vehicle is heavier and more expensive, but is currently a favorite in the European market.
Against this backdrop, SIGMA's strengths include its larger ammunition load and its focus on fully automated firing cycles, coupled with localized production tailored to specific customers.
Technical features
The SIGMA 155 is a self-propelled artillery unit on a wheeled chassis, built using modern technical solutions and with the potential for modernization according to customer requirements.
All SPG modifications are built on a special five-axle chassis with a 10x10 wheel arrangement. For example, the SPG for the US Army is based on the Oshkosh LVSR (10x10) vehicle. The base vehicle retains the standard cabin and controls; the fighting compartment and associated components are mounted on the cargo platform.
The SIGMA's fighting compartment is designed as a full-size armored turret. The front of the compartment houses an oscillating mount for a 155mm gun. Various guns with barrel lengths up to 52 calibers can be used. The turret mechanisms allow firing within a horizontal sector at various elevation angles.
Mechanized ammunition stowage racks are located along the sides of the turret. The original SIGMA carries 40 separate-loading rounds with cartridge cases or propellant charge modules. The round components are extracted from the stowage rack and fed into the chamber by an automatic loader. Manual loading is also possible if necessary.
According to the developer, the SIGMA/Roem is the world's first self-propelled gun with a fully automatic firing cycle. The crew has been reduced to three, compared to seven on the older M109. Loading, selecting the projectile type, fuse, and propellant charge are all done without human intervention.
The robotic turret provides a rate of fire of up to 8 rounds per minute; this rate decreases during sustained firing. A multiple-round simultaneous impact (MRSI) mode is advertised: the gun fires a series of shots along different trajectories so that the rounds hit the target simultaneously.
A "shoot-and-scoot" mode has been implemented. According to the company, the deployment time to the first shot is less than 60 seconds; the dismantling time is approximately the same, allowing the self-propelled gun to leave its position before the enemy responds.
The 155mm caliber gun has a 52-caliber barrel (L52). According to official Elbit data, the basic version (including the Israeli Roem) fires standard NATO ammunition at ranges of 4 to 40 km. The export modification for the US is adapted to advanced American projectiles: the XM1113 rocket-assisted missile and the XM1115 guided missile; according to the manufacturer, these increase the firing range to more than 70 km. The "up to 80 km" figure cited in promotional materials is not the current result, but the planned maximum for the export configuration with the latest extended-range ammunition; for now, this remains a marketing benchmark rather than a proven performance indicator.
The SIGMA is equipped with a digital fire control system (FCS) with integrated navigation, communications, and control systems. Upon arrival at the target, the FCS performs georeferencing, calculates firing data, and performs aiming. Single-fire, salvo, and burst modes are available.
The joint project between Elbit Systems and Anduril Industries is reportedly primarily focused on improving the fire control system and other electronics to meet the needs of the US Army. Future applications include external combat vehicles, reconnaissance UAVs, and command posts. It processes incoming data, helps select a priority target, and calculates firing data. The decision to open fire remains with the human operator (human-in-the-loop). This architecture is intended to reduce the time from target detection to engagement to just a few tens of seconds.
Achievements and plans
Elbit Systems has received and is fulfilling at least two orders for the production and delivery of SIGMA self-propelled guns, participated in a German competition, and is now offering its self-propelled gun to the Pentagon.
To enter the American market, Elbit has embraced extensive localization. Production of the export version is being carried out at the new Elbit America plant in Charleston, South Carolina, using chassis from American supplier Oshkosh and a network of over 300 American subcontractors. This not only reduces the system's cost but also removes legal barriers under the Buy American Act, allowing the system to be purchased directly through the defense budget. An additional factor: Israel purchases its Roem largely through American military assistance grants (FMF), the terms of which also encourage production in the United States.
Thus, the US Army's entry into the market is different from previous attempts. Here, the SIGMA NG has a real niche, opened up by the ERCA failure, but also faces strong competition from European vehicles. Success will depend primarily on two factors: how deeply the self-propelled gun can be integrated into American command and control systems, and how convincing the localization process is. Whether the partnership with Anduril will yield the desired results will become clear in the coming years.
Information