The 155mm Artillery Shell Supply Chain

The Four-Part Pipeline

A complete 155mm round is an assembly of four largely independent products. There is the forged and machined steel projectile body; the explosive fill packed inside it, usually TNT or a TNT/RDX composition; the fuze that screws into the nose and triggers detonation; and a separate propelling charge of nitrocellulose-based powder, in modular bags, that launches the shell out of the gun.

These four come from four different supply chains. Body forging belongs to heavy metals industry; explosives and propellant come from specialised, hazardous energetic-chemical plants; fuzes draw on precision engineering and electronics. A finished round exists only when all four converge in a load-assemble-pack (LAP) facility. That structure is the key to understanding the war's ammunition crisis: scaling one element does nothing if another lags.

It also explains why governments funded the whole chain rather than just ordering more shells. A prime contractor can promise a million rounds, but the promise is only as good as the powder mill and the explosives plant feeding it.

Powder: The First Step

The propelling charge begins with nitrocellulose — cellulose from cotton linters or wood pulp treated with concentrated nitric and sulphuric acid. The resulting "guncotton" is processed into propellant grains and modular charge bags. This chemistry is dangerous, tightly regulated and concentrated in very few plants, which made nitrocellulose one of the first chokepoints to bite after 2022.

Europe leaned heavily on a small set of producers. France's Eurenco restarted nitrocellulose output at its Bergerac site, which had been shut after a 2022 accident, and committed roughly €500 million to lift powder production roughly tenfold and double modular-charge capacity. Rheinmetall, anxious about supply, bought the German nitrocellulose maker Hagedorn-NC and moved to expand its Nitrochemie joint venture with RUAG in Switzerland and Germany.

Because powder is the first link and the hardest to scale, it repeatedly set the limit on how many complete rounds the West could ship — a point explored in detail on the dedicated propellant shortage page.

Explosive Fill

The bursting charge inside the body is most often TNT, sometimes blended with RDX in compositions such as Composition B for greater power. RDX and the related HMX are produced in a tiny number of facilities; in the United States, the dominant source is BAE Systems' Holston Army Ammunition Plant in Tennessee, historically the exclusive domestic producer of RDX/HMX formulations.

TNT itself became a notorious gap: for years North America had no domestic TNT production at all and relied on imports. New capacity is being built — Repkon USA won a US Army contract to establish a TNT plant in Graham, Kentucky, and General Dynamics committed its own capital toward shell and ordnance work in Texas — but energetic-chemical plants take years to design, permit and certify. The detail is covered on the explosives makers page.

The volumes involved are large. Reporting on the US ramp toward roughly 100,000 complete rounds a month cited explosive requirements in the tens of thousands of tons, much of which had previously been imported — another reason the explosives tier became a strategic priority.

Body and Fuze

The steel body is the most scalable part of the chain. Forging and machining shell bodies uses skills and presses that exist across the wider metals industry, so capacity here grew comparatively quickly. The US Army and General Dynamics opened new metal-parts and load-assemble-pack lines, including a large facility in Mesquite, Texas, to push throughput up.

Fuzes sit between metal and electronics. Basic point-detonating fuzes are straightforward, but precision and proximity fuzes draw on the same semiconductor and electronics supply chains that constrain guided weapons. As armies shifted toward precision-guided artillery, the fuze tier began to inherit some of the chip-supply pressures seen elsewhere in defense.

Even so, bodies and fuzes were rarely the binding constraint. The recurring story of 2022 to 2026 was that empty bodies and fuzes were available faster than the powder and explosives needed to fill and fire them.

The EU and US Ramp

Both sides of the Atlantic set ambitious targets. The EU's Act in Support of Ammunition Production (ASAP), enacted in 2023, allocated about €500 million and aimed to lift annual European 155mm output toward roughly two million shells. The European Commission said capacity reached about one million rounds a year in early 2025, with primes such as Rheinmetall adding lines toward 1.1 to 1.5 million by 2027.

⚠ Figures are approximate and from the European Commission (EC ASAP), the US Army (army.mil) and reporting by Defense One and National Defense Magazine. Targets have slipped and change quarter to quarter.

Where the Chain Binds

By 2026 the pattern was clear. Metal-parts forging and final assembly scaled fastest; the binding constraints sat in propellant powder and military explosives. The US Army's 100,000-a-month goal slipped from an October 2025 target toward mid-2026, and the EU's two-million ambition was approached but not hit, precisely because the chemical tiers could not match the speed of the metal tiers.

This is the central lesson of the 155mm supply chain: the visible shell is the easy part. The hard part is the invisible chemistry — guncotton, propellant grains, TNT and RDX — produced in a handful of plants that take years to build and certify. Until those deep tiers expand, the headline shell targets remain aspirations gated by powder and explosives.

For Ukraine, the practical effect is that ammunition supply improved steadily but unevenly, tracking the slowest link rather than the fastest. For Western planners, it reframed artillery resupply as a chemicals problem dressed up as a steel one.